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This site is made, written and updated


 Zainea Liviu





















































































































Roundffusor1 is protected by the United States Patent Nr.: 7261182


European Patent Nr.: 1506541

  The most recent international publication about R1, at ITEM10 is here




Basic data : patents, materials, flammability certification, CE Declaration, prospectus

  First of all, Roundffusor1 is a National Greek Patent  -     Nr.: 100 41 86 / 2002     The R1's paper - ''Acoustics 2002'' at the Patras Univ.- Greece. Proceedings for Hellenic Acoustics, Patras 2002, ISBN: 960-7620-27-5, pp.41-48, 2003.  
  Roundffusor1 is a complex acoustical device - is an active and clean sound diffuser (from around 180-250Hz to 20.000 Hz) & adaptable low frequency absorber (5 - 250 Hz).  R1 its an All In One Small Package.
  Roundffusor1 is not a sound insulation material and is not a construction material.
  United States Patent 7,261,182 -  Zainea Liviu Nikolae. Title: Wide band sound diffuser with self regulated low frequency absorption and methods of mounting
  R1's production : materials

The R1 is produced from Polystyrene Impact 7240 which is a very high impact polystyrene. This grade has been designed to be diluted with crystal polystyrene such as polystyrene crystal 1160,1340, 1540 at high levels to obtain stiff and impact resistant sheet for thermoformed packaging.

    The 7240's granules are then melted and transformed in plates of 5 mm thickness and then using a mould are thermoformed into R1's complex shape. Flammability rating for the molded material for R1 is conforming with the Standard  ISO 9773/1998 or UL94/HB 1.5 mm

  Polystyrene impact 7240 Safety data sheet


  CE - Declaration of conformity

     Roundffusor1 - How to buy it

       Roundffusor1  -  Theory

      Roundffusor1 - our first prospectus

  The R1's published European Patent - EP 1506541 is here. Title: Wide band sound diffuser with self regulated low frequency absorption and methods of mounting it. Inventor: Zainea Liviu Nikolae. This text has being written by the inventor before April 2002. Contains an important note from the PCT International search report for our patent.




About translations: '' Human beings do not live in the objective world alone, nor alone in the world of social activity as ordinarily understood, but are very much at the mercy of the particular language which has become the medium of expression for their society. It is quite an illusion to imagine that one adjusts to reality essentially without the use of language and that language is merely an incidental means of solving specific problems of communication or reflection. The fact of the matter is that the 'real world' is to a large extent unconsciously built upon the language habits of the group.

No two languages are ever sufficiently similar to be considered as representing the same social reality. The worlds in which different societies live are distinct worlds, not merely the same world with different labels attached... We see and hear and otherwise experience very largely as we do because the language habits of our community predispose certain choices of interpretation. We dissect nature along lines laid down by our native languages.

The categories and types that we isolate from the world of phenomena we do not find there because they stare every observer in the face; on the contrary, the world is presented in a kaleidoscopic flux of impressions which has to be organized by our minds - and this means largely by the linguistic systems in our minds. We cut nature up, organize it into concepts, and ascribe significances as we do, largely because we are parties to an agreement to organize it in this way - an agreement that holds throughout our speech community and is codified in the patterns of our language.

The agreement is, of course, an implicit and unstated one, but its terms are absolutely obligatory; we cannot talk at all except by subscribing to the organization and classification of data which the agreement decrees. Individuals who regard writing as fundamental to their sense of personal and professional identity may experience their written style as inseparable from this identity, and insofar as writers are 'attached to their words', they may favor a Whorfian perspective.

And it would be hardly surprising if individual stances towards Whorfianism were not influenced by allegiances to Romanticism or Classicism, or towards either the arts or the sciences. As I have pointed out, in the context of the written word, the 'untranslatability' claim is generally regarded as strongest in the arts and weakest in the case of formal scientific papers (although rhetorical studies have increasingly blurred any clear distinctions). And within the literary domain, 'untranslatability' was favored by Romantic literary theorists, for whom the connotative, emotional or personal meanings of words were crucial''. [from : The Sapir-Whorf Hypothesis - Daniel Chandler]


Our bigger projects: the road from important works to the unique Roundffusor1  

Some of our activities : Room acoustics improvement or new constructions for sound recording facilities: Studios, TV, amphitheatres, music halls or dedicated rooms for listening music. One  project was Thanos Mikroutsiko's recording studio where he already finished enough professional recordings.

 The GIALINO MOUSIKO THEATRO in Athens (the Gialino Teatro's site is here), our most complex project, maybe, is the best music hall in Greece, built with the previous acoustical materials technology and very expensive.

  We design and supervise special sound insulation constructions for any industrial or naval situation.

Our bigger industrial project was a successful prototype sound insulation of machinery engine room to a 110 meters cruise ship ''Princess Danae'' and a much bigger one, a Greek military complex of 16 tank motors testing chambers. It is finished a full project heavy sound insulation, interior acoustical design and 12  KW audio array-a multipurpose hall in Sparta. 

We were invited paper at the Acoustical Society of America's Pittsburgh 2002 Poster Session: Halls for Music Performance: Another Two Decades of Experience 1982-2002. We presented ''THE GIALINO MOUSIKO THEATRO''.

In Greece, a paper about the ROUNDFFUSOR1, was presented at the first Congress of the Hellenic Institute of Acoustics (HELINA)  University of Patras, September 30, 2002. HELINA is a member of EUROPEAN ACOUSTICS ASSOCIATION (E.A.A.).

In Romania, a work about the corrected studios of the State Romanian Broadcasting Co.  was presented at the Second International Conference of Romanian Society of Acoustics on Sound and Vibration (is a member of EUROPEAN ACOUSTICS ASSOCIATION (E.A.A.),14 – 17 October 2004, Bucharest.

> In Romania again, a work about the Resita's renewed and acoustically corrected City Hall was presented at the International Conference of Romanian Society of Acoustics on Sound and Vibration (is a member of EUROPEAN ACOUSTICS ASSOCIATION (E.A.A.), 21- 24 October 2009, Resita .

In the last  months, 15 new recording studios were built or acoustically corrected in Athens, 2 more in Thessalonica and 6 new studios abroad [ 4 in Romania and 2 in Holland ], all using our Roundffusor1. Twelve of them are built using ONLY the Roundfusor1 with or without small carpets on the floor, the same for control room and all recording rooms. In Athens, the new Eurosound's demo room, it was built only with R1 on the ceiling. 

He who rejects change is the architect of decay. (Harold Wilson)    Make everything as simple as possible, but not simpler. (Albert Einstein) The man who cannot occasionally imagine events and conditions of existence that are contrary to the causal principle as he knows it will never enrich his science by the addition of a new idea. (Max Planck)

We excuse that we don't have too many representatives around the world (we work hard on this). Until you will have a representative near to your place, in order to hear and believe that our R1 is indeed so good, please note that there will be always experts to say Forget it: such things are impossible...  

From a study based on 1950's work by a psychologist we have some unexpected conclusions... The unpleasantness of standing alone can make a majority opinion seem more appealing than sticking to one's own beliefs. If other people's views can actually affect how someone perceives the external world, then truth itself is called into question. See more here.

The big challenge

 How we try to improve the World's architectural acoustics data and attitude

The Roundffusor1 is in a totally new category, a giant step in the art of acoustical materials !


 A detailed description of our invention 

The ideal [overall] predicted sound diffuser polar plots, something thought and desired, but difficult to believe as being ever practically produced...



Above, a more specific prediction [using Matlab] for scattering from hemispheres and hemi cylinders, variation with distance.

Regarding the Roundffusor1 which is built from a complex combination of  hemispheres and hemi cylinders , please note that our device when grouped mounted, is simultaneously a very active diffuser and much more complex Helmholtz resonator and, the combination of two is almost impossible to be emulated into an equation. We may say that the superposition principle is somehow the explanation phenomenon, but not only...


This two examples are the ''ideal'' or best predicted polar diagrams ( from bibliography ) for situations similar with the Roundffusor's measurement setup. The heavy lines (hemicycles) represents 99% diffusion factor, and the incidence angles are : a) 0, b) 30 and c) 60°. The Roundffusor1's measurement were made at 45° and the above Matlab calculations are also made for 45°. Please note that the Roundffusor1 was measured with a TEF20, in a range from 12-19368 Hz .

Generally, please note that almost all predicted plots found in the bibliography or other acoustical materials characteristics are results from programs working down to 125 Hz only. As you know [ and the High-End users knows better than all because they are paying hard for this] the bass contents determine the so named ''body'' of music, his bass contour containing a plethora of musical information which transmits to our ears the intimate feeling of each source we are approaching by. So from most PC's predictions, the ''abyss'' bellow 125 Hz is unknown or not included.

The off axis polar plots '' from another company '' (as far as we know that their provenience is reliable), are chosen from the best of their diffusers, also at 45° and similar measurements setup.

We are ''forced'' to say , that the Roundffusor1 polar plots , are similar in many ways with the ''ideal'' ones. Hopefully for us, the listening tests out-performed and anticipated the excellent TEF20 measurements.

We present the following polar plots diagrams from diffusers applications : a) a case study were the R1 was used as room treatment, b)- a QRD diffuser type from an US company and, c) - a gypsum pyramid diffuser from a US Co. You may compare them with the '' ideal ones'' diagrams and have your own opinions.

 Few detailed R1's measurements are here

Cluj - Napoca - Romania. State Radio station control room. All polar plots were obtained from a 45 deg. incidence angle

A case study - Comments:

1. The R1's correction factor it was limited only by the loudspeaker's low frequency capability installed there.

2. The measurements were made into the control room shown below 

3. The Roundffusor1 were mounted directly upon the absorption material found there. After the R1's treatment, the rest of the studios surfaces, except R1's covered ones, remained with the absorption materials as built before.

4. Please note, that R1 was effective even mounted upon and between absorptive materials. The tiles in the ''after'' correction, tends slightly to left indicating that the existing absorptive materials, quantitatively, covered a much more surface on the left surface of the studio as we look at the loudspeakers.

>>> It was demonstrated elsewhere that when relatively bigger absorptive material are used in a room, this surface tends to emulate an air duct's flow directivity meaning that the sound as perception is oriented there like a monaural phenomenon. Needless to say , this will reduce the stereo image...the stereo image will bend towards the bigger absorption surface, like a directed jet fluid.

It is an evidence that using the Roundffusor1 the acoustic field is ''forced'' to symmetry, or ...the wrong stereo image becomes a wide natural well defined stereo image.


Measurements made before the acoustical treatment with R1


Measurements made after the acoustical treatment with R1




63-8000 Hz


125-16000 Hz



The critical Roundffusor 1's measurements

Here are the critical Roundffusor1's measurements (which at a later stage will be provided by the various independent laboratories in order to confirm our measurements and for which I will not pay, because you never have to pay for the near perfection situations) showing that the R1's plastic body doesn't vibrate - so doesn't produce sensible second generation sound/harmonics, and , that the air from the R1's back Helmholtz resonator function is having a double role - first an adaptable damping for low and very low frequencies up to 181 Hz and beyond this and second, that the mid and high frequencies levels are drastically reduced (only from the space of the grouped mounted R1's back cavity) with about 10 to 25 dB , this explaining the dramatically perceived and measurable RT60'S reduction in empty rooms containing only the R1. The front R1's surface, don't forget , is producing the clean diffused field, enhancing the room's loudness field by a factor of 1,5 -2. This is a paradox, and the superposition principle is called to solve it.

Don't forget that in this life and universe, the good luck and intuition or randomness plays a constructive role, name it evolution, or Ancients unveiled dormant memory, sometimes, as in the Roundffusor1's case were a design progression of interrelated phenomena evolved in this patent. To ''switch'' from dormant memory ''data base'' to a higher cognitive development is possible, although by no means easy. So, read otherwise...R1 was designed by mind. Here a relevant text (Chomsky and the Universal Grammar) .

Reading from Carl Jung's philosophy of memory , the ''FIFTH LEVEL: INTUITION ~ This is the ultimate level, where learning becomes connected to your experience. This is the stage where you begin to make connections between things you learn in one class, and things you learn in another. You begin to see that everything connects, in some way. You begin to see the way “the big picture” looks! You have to work toward this level, but the reward is a lifelong appreciation of the very process of seeking knowledge''. And everything is connected to a society - here a new essay by Don Cruse - The Embattled Ideal of an Open Society. Additional ideas : Concerning Science, Religion, Logic, and the Evolution of Human Consciousness, relevant texts here , here or here.

Mind over matter or... ''intuition is to thinking what observation is to seeing (Goethe)''

Or, if you prefer, stay put in the past...   

Diagrams for acoustical materials (diffusers) from another companies

250-6300 Hz

 b) Here are the polar plots of a diffuser (QRD Type) from an US company 





250-6300 Hz

 c) Here are the polar plots from the same US's Co. - a gypsum pyramid diffuser

>>> Regarding the somehow not symmetrical diagrams above (a&b) , it was demonstrated elsewhere that when relatively bigger absorptive material surface is used in a room, this surface tends to emulate an air duct's flow directivity meaning that the sound as perception is oriented there like a monaural phenomenon. Needless to say the stereo image it will be blurred and distorted, yes... the stereo image will bend towards the bigger absorption surface, like a directed jet fluid. If the absorption surfaces are symmetrically mounted upon the lateral walls, then the predominant channel will split in two, like monaural signals.

Diffusion or absorption ?

For more than 70 years ago, prestigious scientists remarked and proposed the use of diffusion instead of absorption in all qualitative acoustical situations. Interfering reflections can be controlled by absorption or diffusion.

In small and medium sized rooms, it is often desirable to control interfering reflections, from the rear wall, using diffusion instead of absorption. In this way you can provide a diffuse ambient sound field, while controlling interfering reflections.

When the room's surfaces are relative close to the listener, a very efficient diffusing surface is needed, this because as known, the smaller the room the most difficult to smooth the many resonance modes. To solve this problem, ONCE AND FOR ALL,  ESR by its owner and acoustical consultant Zainea Liviu, designed, patented and then produced the ROUNDFFUSOR1.

When the shape / geometry determines the function, in the design effort, subconsciously, it may reach the Mandalas sacred symmetry or the Chladny evident also symmetrical situations. More, perhaps I was influenced in its design by the purity and simplicity of ancient Greek art. As much as archeology unveiled the past, the ancient Greeks used no absorptive materials in their theatres, just hard materials and ingenuity...The subjective geometry / aesthetics perception should be subordinate by the very performance, an unique situation in the architectural acoustical field.

Now, the Roundffusor1 it is the industry first, and from far away, the most efficient sound diffuser.<<  I agree that all this statements are at the edge between self-confidence and arrogance, but please, take all this as self-confidence or deep joy resulted from the outstanding invention's performances. And deep joy from musicians using the R1, is much more satisfactory and comes to me all the time.  >> 

I am indebted to the earlier work done by Peter D'Antonio, PhD & CEO and his collaborators at the RPG Diffuser Systems. Without their previous efforts, my invention couldn't be so quickly possible.<< But, a  good initial idea - a prototype for ultra sound metallic diffuser (M. R. Schroeder, around 1975) being ''adapted for audio range'' and commercialized continuously in ''small pieces'' is not real progress.

About real technological progress you may read '' The Law of Accelerating Returns'' by Ray Kurzweil. 

Architectural acoustics ?

You choose the Music Hall's geometry

We solve the acoustical problems !

We can also tune your existent room to subtle musical requirements

'' The perfectly * diffuse sound field ''

Even though unattainable ( they said ) , it is instructive to consider the characteristics of a diffuse sound field. Randall and Ward’ have given us a list of these:

• The frequency and spatial irregularities obtained from steady-state measurements must be negligible.
• Beats in the decay characteristic must be negligible.
• Decays must be perfectly exponential, i.e., they must be straight lines on a logarithmic scale.
• Reverberation time will be the same at all positions in the room.
• The character of the decay will be essentially the same for different frequencies.
• The character of the decay will be independent of the directional characteristics of the measuring microphone.

These six factors are observation oriented. A professional physicist specializing in acoustics might stress fundamental and basic factors in his definition of a diffuse sound field such as energy density, energy flow, superposition of an infinite number of plane progressive waves, and so on. The six characteristics suggested by Randall and Ward point us to practical ways of obtaining solid evidence for judging the diffuseness of the sound field of a given room. From :The Handbook of Acoustics-3rd Editions- F. Alton Everest, TAB Books, page 223. (* Personally I don't agree with the term '' perfect ''. For this reason I use ''near perfect'', even if the Roundffusor1 is making beautiful and ''perfect'' the sound of music.   



What is the Roundffusor1 and how it works

We present here a new kind of a sound diffuser, enough simple in his construction but very active in doing his job. It is composed from a main body and two lateral drivers. This two drivers serves to sustain very steady the diffuser upon the surface to be mounted: walls or ceiling. This diffuser may be used in any kind of room where the critical listening is needed. His main advantage is that it is working simultaneously in two ways: as a clean diffuser for mid and high frequencies and as a self controlled absorber, below 250 Hz, for low and very low frequencies. This is possible, because being mounted in a new way, works like a complex Helmholtz resonator.

In real time, there is a kind of reconstruction of all music characteristics – parts diffused or absorbed or both. Even for the trained ears, there is no time to percept when and how the music is processed and the listener is just immersed in the sound without any trace of coloration. The ‘’ historical’’ focus place of listening, become obsolete.

The invention is relative simple as an object but being very easy to be installed  by anybody with simple tools and being also very cheap , will let the people to buy their beloved stereo equipment or professional electronics and put them in a room where the acoustical environment will become also... a ''professional tool''. 

Believe it or not, this ''tool'' exists - there is no other like this and in the rooms treated with our Roundffusor1 there is no place and no need for any other acoustical material. The reason is simple: the Roundffusor1 is doing all that is necessary on a minimal surface.

It's the useful change and I'll not exaggerate at all that, regarding the audio field, after the phonograph, transistor & valve and the audio CD, the Roundffusor1 is the most mass orientated product on the market.

I'm fully responsible saying that all other acoustical materials besides their more or less announced and true diffusing function, are ''performing'' a so much damage on mid and high frequencies - there when the music plays, so much that the absorption ''induced'' is actually removing the essential from music.  

In fact, the inertial ''traditional'' absorption removes the natural feeling of a real human musical performance !


Perceptual observations

Regarding the precedence effect, it is also soften. Axial or left / right head movements don’t arrives to dramatically induced changes. There is an incredible stability of sound image. At the first sound heard from the loudspeakers, the listener, instinctively [meaning very quickly, something between 0.1 to 1 second] focus the ears/ eyes on the location of each musician. During the music, all those spatial references, are easily memorized / visualized by the listener. More, if the musicians changes their places, or are moving here and there, their movements are easily sensed. In a way, you may  VOTE  to  see what kind of ''room decoration'' is your preferred one.

The Roundffusor1 have NOTHING in common with the ''QRD - Diffractal / RPG'' type diffuser, or with any of their products, just being much better overall and of course substantially less expensive.

One of the things that might be a key ingredient in the design of R1, is that scattering from spheres / hemi spheres produces focusing on a line behind the sphere. This line lies inside the wall , considering the original source, but the scattering from the virtual image source will focus sound into the room. Thereby the scattered sound may be heard at long distances from the R1. The same might happen with the cylindrical parts of the R1, but to a lesser degree. In this way the scattered sound may perhaps be audible at longer distances from the R1 than from other diffusors. Because real sound sources aren't point-like, and since the hemispheres on an R1 wall are close to other scattering objects, the focusing will be somewhat smeared, which in turn might reduce any negative effects of focusing.

The Roundffusor's subjective phase perception ( and easily measured ) is near zero phase or, more correct - no irregular phase curves, regardless the center frequencies or music bandwidth. All this phenomena are valid and perceived at more than 6-7 meters - for average audio cultivated people and even to 12-14 meters for very trained ones- from the music source and the '' critical focused point of listening '' or '' sweet <stereo> spot '' is obsolete. 

Normal discussions are easy in the rooms fitted with Roundffusor1 - the voices are clear and not influenced / disturbed by the acoustical field. Speaking, you understand that the room is almost empty from '' strange materials'' , but any kind of echoes or anything which may interfere and disturb the intelligibility are simply NOT THERE.

For music, a kind of ''aura'' envelope reconstruction from the initial room's recording session is obtained. The clean perception for speech or music arrives at all levels- from about 50 dB SPL to the personal pain limits. Think that all this arrives from a very hard plastic area-of at least 9 Roundffusors1, mounted on the back wall or ceiling and, ... there is nothing to be changed on your electronics.  




Here is an interpretation about the damages ''obtained'' when using absorption in a room dedicated to music: '' As a result, the "naturalness" of recorded is destroyed, and its ideological effect severely curtailed, if not totally obliterated. The result is double-alienation, both material and formal there is an emphasis of distance-the distance between the musician and the listener, the distance created by the mediation of recording and playback technology. Unlike with less self-critical rock, there is no "insistence that nothing a man comes in touch with may be better, or may be regarded as better, than he himself is or thinks he is" (28). The lo-fi listener encounters a form, as a form-and not any transparent font of "emotion," etc. The music may still be pleasurable, but it is pleasure in a cultural product which refuses to be merely what it appears to be, which constantly puts its very ontological status into question. In a world dominated by the cultural industry and its products, such pleasure seems to be, in a way, progressive-even if not in the sense that Adorno would favor. [Play "It's Only Lena."]''.


The live or recorded music will sounds beautifully similar from room to room




The inventor - Zainea Liviu Nikolae

What matters ? The quality of the Invention or the tenacity of the Inventor ?

The people perceive only the quality of the Invention

The Roundffusor1 was invented by Mr. Zainea Liviu Nicolae who studied mechanical engineering at the University Brasov - Romania. Mr. Zainea is member of HELINA and American Acoustical Society, being an acoustical consultant and a freelance sound engineer. His published technical articles/papers are posted in this site. It is listed in the Who's Who in the World & Science & Engineering for the 1996-2009 editions and IBC - The Lifetime of Achievement One Hundred.

Some important psychoacoustical aspects when R1 is used: the sweet spot becomes obsolete, a perceptible EDT's reduction, the masking produced by the low frequencies is lowered, an estimated 1,5-2 dB of loudness increase. This enhancement may be explained as a statistical coupling of incident and scattered waves.


1. The traditional boring sweet spot becomes obsolete. The self adaptive bass  absorption offered by the Roundffusor1 removes the harmful dynamic masking effects induced by the low and very low frequencies toward the right of the audio scale. Thus small edit and control rooms filled with our Roundffusor1 are from now on historically optimized regarding their energy balance in all low frequency bands.  

 2. Effectiveness of pure tone maskers (frequency as indicated, presented at 80 dB SPL). As you see , the 250 Hz masker have the wider and powerful influence. The 3 tones are presented simultaneously to the ears , and as lower the frequency is , as much his masking is more extended, even if at low frequencies the modes are fewer -our note ).

As much the masker is of a lower frequency , so much his influence covers to the right of the audio band. If the above is valid for tones, think about the dynamic masking imposed from various low frequencies in a two channels spectrum from music... Based on data of R. Ehmer1959- here is the article.


The self adaptive bass absorption offered by the R1,removes the harmful dynamic masking effects produced by the low and very low frequencies towards the right of the audio scale. Here is our analysis with some psychoacoustics conclusions. [click here].  

The theory that the mind works like a computer, in a series of distinct stages, was an important steppingstone in cognitive science, but it has outlived its usefulness, concludes a new Cornell University study. Instead, the mind should be thought of more as working the way biological organisms do: as a dynamic continuum, cascading through shades of grey. New Cornell University study suggests that mental processing is continuous, not like a computer. In humans the neural activation patterns flow back and forth to produce nonlinear, self-organized, emergent properties of a biological organism and their resolution of the ambiguity is gradual rather than the discrete 0 and 1; it's a dynamical system." If there was ambiguity, the model assumed that the mind jumps the gun to one state or the other, and if it realizes it is wrong, it then makes a correction.

Michael Spivey, a psycholinguist and associate professor of psychology at Cornell wrote: "In thinking of cognition as working as a biological organism does, on the other hand, you do not have to be in one state or another like a computer, but can have values in between -- you can be partially in one state and another, and then eventually gravitate to a unique interpretation, as in finally recognizing a spoken word.’’ Regarding speech recognition, he argue that the older models of language processing theorized that neural systems process words in a series of discrete stages, the alternative model suggests that sensory input is processed continuously so that even partial linguistic input can start "the dynamic competition between simultaneously active representations." 

We believe that listening instrumental music doesn’t need so much ‘’brain computing’’ but when various kind of masking are present the well known or dynamically remembered musical patterns flow back and forth trying to ‘’put back’’ the missing (masked) music details and, if the acoustical environment is not appropriate for clear listening (because of too much damping / absorption or too much reverberation), those ‘’missing parts’’ (being below the subjective / personal perceptive threshold ) are ignored, and... gone is the aesthetical pleasure as initially intended by the very composer -  musician/s.

Here below, there are some technical , physiological, psychological, technical and aesthetical considerations regarding a professional or a personal session of judging a recording in an acoustically treated room - be a recording or broadcasting studio or a room dedicated to music listening,  in a normal, Hi-Fi or High-End category.   

Table 1.  Parameters and examples of common descriptive terms

(taken from EBU Doc.Tech. 3286/10) 

Main parameter Sub-parameters Examples of common descriptive terms
1. Spatial impression
The performance appears to take place in an appropriate spatial environment -    Homogeneity of spatial sound

-    Reverberance -    Acoustical balance -   Apparent room size -    Depth perspective

-    Sound colour of reverberation

Room reverberant / dry; Direct / indirect; Large room / small room
2. Stereo impression
The sound image appears to have the correct and appropriate direc­tional distribution of sound sources -    Directional balance -    Stability -    Sound image width -    Location accuracy Wide / narrow; Precise / imprecise
3. Transparency
All details of the performance can be clearly perceived -    Sound source definition -    Time definition -    Intelligibility Clear / muddy
4. Sound balance
The individual sound sources ap­pear to be properly balanced in the general sound image -    Loudness balance -    Dynamic range Sound source too loud / too weak; Sound compressed / natural
5. Timbre
Accurate portrayal of the different sound characteristics of the sound source(s) -    Sound colour -    Sound attack Boomy / sharp; Dark / light; Warm / cold
6. Freedom from noise and distortions
Absence of various disturbing phe­nomena such as electrical noise, acoustical noise, public noise, bit errors, distortions, etc.   Perceptible / imperceptible disturbances
7. Main impression
A subjective weighted average value of the previous six parameters taking into account the integrity* of the total sound image and the interaction of the various parameters.

Terms : more detailed explanations. From (EBU TECHNICAL REVIEW – September 2000 8 / 17 ,G. Spikofski )

 It can be generally assumed that, in professional audio environments, the "neutrality" of the listening conditions is an indispensable requirement. However, the definition of "neutrality" is a complex issue as the sound field in listening rooms is influenced by a variety of parameters. In a listening room – in contrast to headphone listening, which is determined solely by the properties of the transducer used – the loudspeakers, the room and local relationships between the loudspeakers and listeners interact in a complex fashion. This is true of monophonic, stereophonic and multichannel listening.

In other words, if one considers a conventional music transmission from a single sound source in a concert hall, the listening experience from the reproduced sound will be characterized by an overlapping of the "primary room information" (i.e. from the concert hall) and the "secondary room information" (from the listening room). Seen in this way, "neutrality" can be defined approximately as follows: the listening room enables the sound producer to work in a familiar "room" environment, rather than in an unfamiliar "anechoic" environment.

The influence of the room may be just perceptible enough for the "primary room information" not to be drowned out. "Neutral listening conditions" are a necessary instrument for aesthetic quality assessment in music production. In broadcasting, this is of particular importance in the field of international programme exchanges. With the introduction of new transmission and storage systems based on aurally-adapted data compression, neutral listening conditions are a necessity from another angle: only in neutral listening conditions is an objective assessment of the quality of the new generation of audio systems possible. Technically, the definition of "neutral listening conditions" involves setting minimum requirements for the relevant electroacoustic and acoustic parameters. Standards bodies have been working on the optimization of these parameters for decades.

 Coloration: The typical attributes of this factor relate to sound colorations ("coloured", "uncoloured") due to linear (frequency-dependent) distortions. This aspect is of particular importance for the quality assessment of listening conditions, since the general quality attributes "natural" and "well-balanced" correlate closely with coloration.

 Tonal balance: The typical attributes of tonal balance relate to the reproduction of bass and treble frequencies. Apart from the reproduction of bass and treble sounds ("emphasized" – "deemphasized"), another factor to consider is the relationship between bass and treble sounds. This becomes clear if one considers the correlations between the attributes "treble emphasis – lacking bass" and "bass emphasis – muffled" (in the sense of "lacking treble").

 Imaging quality: The attributes relevant to interpretation of this factor relate to the room and the (phantom) sound sources which are simulated with the aid of stereophony in the loudspeaker base area. The attributes "stage width" and "stage depth" describe the imaging of the simulated sound source, e.g. an orchestra, relative to the dimensions "spatial breadth" and "depth". Good spatial depth of the sound source is described with attributes such as "exactly localizable", "transparent", "detailed" and "spacious", which are contrary to the attribute "blurred".

 Reverberance: It can be assumed that reverberance, as a relevant psychoacoustic factor, correlates with the sound-field parameter "reverberation" in the listening room''.

Conditions: Listening panel

The listening panel should be composed of listening experts, that is people who understand and have been in trained in the agreed method of subjective quality evaluation. These listening experts should:

  work daily in the production of sound programmes of the subject genre chosen for the evaluations or have extensive experience in listening to sound in a professional way,

  have ontologically normal hearing: ISO Standard 389 [3] should be used as a guideline. (Ontologically normal person: A person in a normal state of health who at the time of testing is free from all signs or symptoms of ear disease and from obstructing wax in the ear canal, and who has no history of undue exposure to noise.)

be reasonably fluent in the working language of the evaluations, because verbal expression is an important part of the method.  

Explaining the ''grade'' significances, below (same source)




Very annoying defects


Too many annoying defects


A number of annoying defects


Some slightly annoying defects


Some perceptible but not annoying defects


No perceptible defects

Table 2: Impairment grades




Bad. Substantial technical defects. Unsuitable for transmission.


Poor . Should be used for transmission only in exceptional cases. Only of documentary value.






Vary good



Table 3: Qualify grades

EBU- Assessment methods for the subjective evaluation of the quality of sound programme material- Music

You may see, that very easy , when Roundffusor1 is used, all parameters becomes ''excellent/ no perceptible defects''. The ''Freedom of noise'' was on purpose let somehow lower, because we perceived that even in normal , residential rooms, treated with R1, rooms not constructed as recording studios with highly degree of sound insulation, all the above parameters takes a ''6'' sort of the R1's unique plethora of qualities.

From : EBU – Listening conditions for the assessment of sound programme material: Monophonic and two–channel stereophonic - t e c h 3276

Fig1  Tolerance limits for the reverberation time

Reverberation field

Reverberation time: Figure 1 shows the tolerance field for the reverberation time, in accordance with EBU. The measurements are made with the used loudspeakers and with 1/3-octave band filtering. Tm is the arithmetic average of the measured reverberation time T in the 1/3-octave bands from 200 Hz to 4 kHz. It should lie between 0.2 and 0.4 seconds, in dependence on the room size in order to allow a ‘natural’ spatial perception. The frequency response for the reverberation time should be steady and continuous; sudden or strong breaks influence the operational sound level curve. Therefore such deviations in adjoining 1/3-octave bands in the region of 200 Hz to 8 kHz should not exceed ± 0.05s, and less than 200 Hz less than 25% of the longest reverb time should not be exceeded. 

Reverberation is the effect caused by multiple reflections from the boundary surfaces of the listening room, which reach the listening area after the early reflections (time delays more than about 15 ms). The reverberation field should be sufficiently diffuse over the listening area to avoid perceptible acoustic effects such as flutter echoes The reverberation time is an important characteristic of the reverberation field; it is defined as the time taken for the sound to decay to 60 dB below the initial level. It is usually measured over the range from 5 dB to at least 25 dB below the initial value. The decay time of the measuring instrument and the filters should be shorter than the decay time of the reverberation field.

The reverberation time should be measured in the listening room with 1/3rd octave filtering [1] using the listening loudspeakers as the sound sources. Reverberation time is frequency–dependent. The nominal value, Tm, is the average of the measured reverberation times in the 1/3–octave bands from 200 Hz to 4 kHz. The nominal reverberation time, Tm, should lie in the range: 0.2 < Tm < 0.4 s in dependence on the room size. To ensure that the acoustic environment remains "natural", the value of Tm should increase with the size of the room. The following formula is given as a guide:

Tm = 0.25(V/V0)1/3 s

where: V = room volume in cubic meters

V0 = reference room volume of 100 m3.

The reverberation time T, measured in 1/3–octave bands over the frequency range from 63 Hz to 8 kHz, should conform to the tolerance mask shown in Fig. 1. In addition, sudden changes in reverberation time with frequency should be avoided and the differences,  T, in reverberation times between adjacent 1/3–octave bands should not exceed the following limits:  T < 0.05 s for 200Hz < f < 8 kHz , and T< 25% of longer time for  f < 200 Hz

The reverberation field should be sufficiently diffuse (linear decay) over the listening area to avoid perceptible acoustical effects such as flutter echoes.

Reverberation Time. The analysis of the reverberation time RT60 in small highly damped rooms is difficult because of sparse room modes and seldom a systematic decay as in large rooms. High RT60 is not desirable in control rooms. Control rooms with very short RT60 were introduced in the 1960’s, but most people find them uncomfortable and tiring when working long hours. With multichannel or modern control rooms, the question of adequate RT60 opens again with direct energy and localization cues coming from all directions.

You may see that with the introduction of our Roundffusor1, the very active diffused field produced by the R1, have a practical resemblance with the reduced RT60 provoked by traditional absorption materials , and we say it once again, without the harmful psychological and physiological effect perceived from soft absorptive materials. In no way we don't try to impose our invention by force. The remarkable results such as indicated in this site speaks by themselves, architectural / aesthetical  considerations being over balanced by sure acoustical results.

EBU tech3276 recommendations : Operational room response curve   

The operational room response curve is defined as the frequency response of the sound pressure level produced by the loudspeaker /s at any listening point. The test signal for this measurement is 1/3–octave filtered pink noise, as specified in [1]. The operational room response curve is an important criterion in the evaluation of the mutual influence of the loudspeaker and the listening room, and hence for the assessment of the listening conditions. It corresponds well with the subjective assessment of reproduced sound. Tolerance limits for the measured operational response curves are given in Fig. 2. Lm is the mean value of the levels of the 1/3–octave bands with centre frequencies from 200 Hz to 4 kHz. The tolerances should be met for each (main) channel separately. For stereophonic reproduction, the close matching of the room response of each channel is important.  Tolerance limits of the operational room response curve. It is recommended as +/- 3 dB for 50- 2000 Hz and +3/-6 dB for the 2000- 16000 Hz. Smoothing: 33% or 1/3 octave bands.

Fig. 2 – Tolerance limits of the operational room response curve. From EBU tech3276 recommendations


Fig.3  Measured room response curves in different listening rooms: mean values and standard deviations in relation to frequency. From (EBU TECHNICAL REVIEW – September 2000 8 / 17, G. Spikofski )

ESR's case study - Fig.4 and 5. Many TEF20's (overlays) measurements (demo room ''Studioanalysis''-Athens, shown at ''STUDIOS'') made with a condenser microphone (put in the a cardioid mode) facing in many places the walls surfaces at some 15 cm distance (the mike facing the wall's surface not the sound source), one speaker active, on the right of the studio's console. Please note that the spectrum's details, varies very little with the distance or orientation relative to the loudspeaker. In this special case study (because the room tends to a cube shape) the ceiling and the floor were left reflective (no coverings) and the total surface around the walls covered with small patches of soft carpet was less than the total floor surface as recommended in previous situations. Will be shown that even like that, the overall TR60 was 0,4 s with no traces of echoes (TR60 in 1/3 octaves: 63 Hz=0,54s,125Hz=0,39s, 250Hz=0,39s, 500Hz=0,41s, 1000Hz=0,47s, 2000Hz=0,46s, 4000Hz=0,41s, 8000Hz=0,38s, 16000Hz=0,41s).The slop was parallel with the Schroeder's RT curves (RT60 decay) in  almost all octaves. This means, that with a careful Roundffusor's positioning and small patches of adequate carpet, we can let the floor and the ceiling fully reflective. 


Fig.4. Many TEF20's (overlays) frequency measurements (demo room at the  ''Studioanalysis''- Athens)   Fig.5. The RT60 at the same demo room

Early reverberation part analysis - Sound samples: the w1.wav(near the sound engineer's place) and  w3.wav(room's right corner) are two recordings made in the demo room ;the w8.wav of the same word ''best'' was recorded in the coupled rooms - hall /''A'' office. The recordings were analyzed with the ''SpeechStation2''. Each record 0,5s, made with a Neumann U89i, no EQ or compressor, no Effects. We compare the content (energy/frequency) of the word's ''best'' first part (b/e) with the syllable (st) in w1 and in w8 (office). It is obvious that the (b/e) in w1 doesn't inject further energy and in this way the spectrum below the (st) is clean of residual energy instead of the w8's case were the bigger reverberation ''linked'' the parts of the word. We have to note that even in empty with reflective walls rooms there is a partial diffused field just that it's timbre is more than often, not nice, not pleasant.

Speaking music, until now, just by listening, I believe that the R1 are doing a kind of residual reverberation extraction from the continuum signal/room , and not just calming the - typically speaking -room resonances [ attenuating the musical ones not in consonance with the direct signal ], in other words the R1 is rejecting the musical dissonances making the atonal music sounding more like temperate/ ''classical'' scales , if such an expression is permitted...

By unfortunate inertia, the people prefer damped and very dumped rooms because they didn't heard or weren't advised to hear clean diffused sound. Almost all music halls built before around 1930 and back to the antiquity, were diffusive and except the people and the chairs there are no other big surfaces of absorptive materials.

Spectrogram 1 - the word ''best''- w1.wav recorded near the sound engineer's place in the demo room


Spectrogram 2 - w8.wav of the same word ''best''  recorded in the coupled rooms - hall /''A'' office


In the spectrograms: with green color- the formants, with red color- the pitch

  Here above we have the clear acoustical diffusion's benefices

When and How does the grouped R1 works ?

why is so important?



When the Roundffusor1 are used as the sole room treatment [any kind of room or music hall or cinemas], even if we remember or not the Shannon theory of information [ where 0 means non or lost information and 1 being the transmitted and understood /perceived message - for us the meaning of a song's words and context and the music's details] all room acoustical imperfections are or tends dynamically to me corrected. With the R1, what more than 99% of listeners perceived is an obvious clearer sound without any trace of any kind of echoes (echo cancellation obtained in a purely acoustical way), the overall room time coherence containing all the details from the source.

The 25-35 msec interval where the named preceding effect arrives and makes distinct two or more reflections is ''embedded'' and masked into the diffusion field. The loudness [one of it's definition being ''the perceived sound intensity when we are focusing our attention towards the sound'' ] is freely and suddenly perceived even by the hearing impaired people. The estimated 1,5-2 units of loudness increase is a clear explanation of R1's adaptability and a confirmation of the diffusion superiority against the old and too tired absorption. More, a direct result of using the R1 is a perceptible EDT's reduction, becoming sensible smaller then the RT60. It is known that the EDT is considered as the subjective way for us to perceive the character of a room along with it's reverberation (RT) timbre and ''RT's tails'' (which for the EDT -Early Delay Time, is a kind of RT10 ). If EDT is bigger or similar with the true RT60, then the room's intelligibility is reduced and along with it, and the musical details, covered by the reverberation time's envelope.

Shorter EDTs generally mean better communication and clearer & natural recordings, since room falls off more quickly and masks the information to a lesser degree. Those facts may be expressed also in this way: ''The increase in the scattering coefficient decreases the amplitude of early reflections, time-smears the non-specular scattered energy, and changes the relative balance between direct, reflected, and reverberant energy'' (from Edge Diffraction and Surface Scattering in Concert Halls: Physical and Perceptual Aspects, Rendell R. Torres, Nicolas de Rycker and Mendel Kleiner). It's exactly what we indicated (more than one year) earlier, on the left diagram, our conclusions being similar with the above ones with the addition that from a clean, increased diffusion, the direct field's content is more dense, real life's timbre - so no traces of coloration.

Along with the goal of a shorter EDT, we must be able to measure some parameters related with intelligibility and process the results into a score (see Fig.5) that correlates with how a human listener might judge the intelligibility. This parameters are: a) the Speech Transmission Index or STI  (the results are processed into an intelligibility score that ranges from zero - bad to one - excellent and  b) the Percentage Articulation Loss of Consonants (%Alcons)- positive numbers are desirable. In all rooms treated with Roundffusor1, the EDT was smaller than the true RT60.

  At the recent International Conference of Romanian Society of Acoustics on Sound and Vibration 2004, held in Bucharest / Romania , after the presentation of the three newly corrected Radio station's studios of the State Romanian Broadcasting Co. using our Roundffusor1, from the immediate round table discussions, resulted once again the difference between the actual state of the art of a practically constructed recording studios -with the specific subjective conclusions and the obvious inertia of strictly applying the actual acoustical standards and interpret ting the results analogous with the standards. And the subjective appreciations (in our 3 cases) were enough different from what ''should'' be the ''letter'' of some standards. In the work presented, were shown the acoustical measurements before and after the R1's mounting upon the acoustical materials found there. In the R1's situation, some standards have to be revised. Was a clear recognition, that our R1 is a huge step forward in acoustics.

Bellow is a R1's simplified analysis (adapted from Torres et al 2004). Intuitively, the Huygens constructs (initially introduced to explain light scattering) from the whole convex / semispherical complex surface will results in an elongated- in phase with the source- orientated hemispherical 3D highly uniform scattering wave lobe. Please note the coupling between each R1's back cavity with the one below and above [the coupling between the single Helmholtz resonator -each R1], all this in parallel columns or rows [depending on the supports direction toward the ground]. Thus, the horizontal diffused lobe field is at a perpendicular angle with the resonating /filtered field emerging from the grouped R1's complex cavity.

Sort of R1's reduced thickness, the diffraction on the lateral wood's supports side is very low but on the other two open sides , a kind of additional scattering might appear. This scattering of diffused field sound by the filtered sound from the complex R1's inside one, might produce transitional /constructive interferences related to the frontal incident wave field which is the music- a dynamic field. The measured phase of those two perpendicular fields are similar and without irregularities. This, correct in a way the known bibliography speaking about phase curve deformations.

As seen at ''R1's critical measurements'' (at R1'1 Tests) each vertical of mounted R1's column acts differently towards the local eigenfrequencies. Internal R1's filtering means that the R1's cavity self resonant frequencies interact with the harmonics of a sound wave passing though each columns. Basically, the result is that the harmonics from the incident field near the resonant frequencies are enhanced, while those away from them are damped [remember the organ situation]. This is for a normal situation. In the R1's case, it's adaptable filtering means that this complex internal interaction map the musical field, correcting it in a musical way. As the musical instruments stays such a long time in their traditional shapes, the same for the R1 which may be considered a musical instrument...

The complex  Helmholtz resonator  which is formed by the back geometry of the grouped R1 are enough similar with the air resonances of closed-box musical instruments were all kind of resonances play a much more active role in shaping the sound. Air modes – resulted from resonance related to the direct sound in the R1’s case -  can have a pronounced affect upon how acoustic energy flows through the entire system, causing subtle changes in the volume and sustain of the vibrations induced in the soundboard by the strings, and ultimately, the timbre radiated to our ears.  

The resonating air  behind  the grouped R1s as the air inside a real musical instrument has many modes of resonance, all occurring simultaneously, all filtering and shaping the final sound we hear. The more the space is divided up into smaller sub-spaces, the more resonant frequencies there are, all interacting with one another to create a complicated and unique mixture - a musical one. That’s why the R1 are so musical and best suited for any kind of music .


More, from the paper ‘’Influence of surface scattering characteristics on the sound quality of reverberation’’ of Jacob Mueller, Mendel Kleiner, Ning Xiang, and Rendell Torres there are some subtle results for the late reverberation, even if not as clear, indicating that the ‘‘individual’’ sound of scattering surfaces will influence primarily the sound quality of the early part of the reverberation.

when does the grouped R1 work ? why is so important?

This must be just another reason on why our R1 is so efficient and subjectively performant sort of its unique shape. Seems that our brain along with the auditory system searches the most sensitive part – the early delay time (EDT) of the reverberation time and is searching for pleasant or not minute tails. Inside of the named EDT, the qualitative EDT’s content influences our senses in the first time/ moments (in fact in the first 100 msec) when we hear music, sound generally. To be more precise for a listening room with a typical RT60 = 0.4- 0.5 seconds, the brain is immediately aware about the sound quality from the first or dynamic time parts of maximum 100 ms (or 0,1 second) each. All this dynamic time parts are panned in 3D and each room at a certain moment as a sole overall EDT, a kind of room's fingerprint. A recording, even filled with plenty of electronic reverberation contains this ''fingerprint'' or a statistical time hologram which may be recognized between two notes or words. Seems that the R1 ''manages'' to make musically the link between the smaller dynamic time parts and larger sound events scales, musically meaning the feel of natural sound, the natural timbre.

I believe that the grouped R1's surface acts like a double acoustical antenna, working in small/ imperceptible fractions of time, in and out, like the ''Stargate's'' opening in the well known and made TV serial. The R1's back interior column's air vibration [designed to calm the room's resonances], ''dictates'' in phase to the front diffusion surface / room's diffused field. This complex antenna have a high gain adaptable (scattering intensity) to the source's level/s - difficult but not impossible to demonstrate/prove (the distributed scatterer such as turbulence or,... a Gaussian distribution of the amplitude of initial field ) being -perhaps- the manifested loudness increase in the room sensed even at 12 meters away from the R1's grouped surface. That's why we choose a short word ''best'' to analyze some rooms. This presumption must explain why even room off-center pair of sound sources are perceived on room's axis with an astonishing wide image sort of the R1's active high gain, the result - to be found everywhere in the room, being a statistical time/frequency like hologram, this ''particle'' information containing  the stereo mix in all details.

We are aware that other researchers believes that combining periodical with a-periodical geometrical shapes on their mounted acoustical materials, the non-uniformity diffused lobes encountered in all theirs materials having periodical shapes will be somehow minimized.

What we know for sure is, that in the Roundffusor1's case - which is a highly symmetrical so of a periodical when grouped mounted shape, the resulted 3D diffused lobe is at the limit of the polar plots ideal / perfection. Analyzing in detail the Schroeder's RT curve's slopes, they were plotted almost 99% parallel in all octaves, meaning that the sound field was indeed being produced diffuse (highly or perfectly, as you prefer) by the grouped R1s so the measured RT 60 or any kind of RT, was conform with the theory. In addition, if we mount an R1, on both lateral walls near the listening position by changing their heights equally, one may vary the depth and the height of the perceived sound, meaning controlling at will the sound stage. This confirms, once again, that the Roundffusor1 is in a totally new category, a giant step in the art of acoustical materials.

There are also some opinions from academics, such as Dr. Roger Penrose of Oxford University, who argue that brains do not work in a way comparable with a computer, so any kind of simulation of the brain that is built on digital architecture and uses traditional programming techniques is doomed to failure''... 


{ such things are impossible ? }


  when does the grouped R1 work ?

I believe that our brain considers those small parts of sound context (duration ≤ EDT and the JND - just noticeable differences - related with all sort of differences in aural perception resulted from  some 17 cm distance between our ears) and dynamically is comparing them with our memory - educated musically or not.

Referring to the non digital way of working of our brain, there is no big surprise that many people really loving hearing music keep and enlarge their LP's collection and at the recording studio level, main path electronics are using tubes / valves (considered ''analogues'') or software emulating old /vintage valve gear- especially compressors.

The ''brain's'' road from 100 ms down to around 2 msec. I spoke about he qualitative EDT’s content influences our senses in the first time/ moments (in fact in the first 100 msec) when we hear music - sound generally, then about the 25-35 msec (milliseconds) interval where the named preceding effect arrives and makes distinct two or more room reflections, then about the first direct sound path of 2,5 -  3 msec from one loudspeaker to the shortest path - supposed an observer, then about the continuum - tympanum / inner ear / nerves / brain. But, when does the grouped R1 work ?

Here is my idea , after so many years of searching it. Why I insist so much about symmetry in the room? Like that we have a field ''ready'' for the original field of the recording, there will be minimal interferences between them. With the help from the R1's diffused field, your CDs or LP or movies will sound like the original ones, with their perfection (meaning the reality at the recording's moments and space) or imperfections. A blend of music lovers dreams with the real high fidelity.

And all this, is done practically simultaneously with the incident sound, because our hearing system cannot perceive...when. Don't forget that the tympanum have equal air pressure above and below, the same with R1's surface. This ''when'', in my opinion is the human perception's delay. Is the time of Summum bonum of all firings in the continuum - tympanum inner ear nerves brain and all the (neurons or cells) firings takes some time something under 2 msec or less..

This ''time'' depends on room dimensions and source/s position/s. Might be considered a human constant but depends slightly on aural human ability obtained from education or selective listening from live or recorded music.  From all musical parameters, the timbre is predominant and this cannot be perceived so fast because an active listening is needed and this requires an active memory use, a comparative one. It is true that all those ''sensations'' are synchronized in around 100 ms when ''what we hear'' is ''compared'' with what we know and we are ''entering'' in the ''like / dislike'' moments being ''locked'' in our brain along with the music. 

Simply said- in the interval of around 2 msec to 1 sec we begin to ''understand'' what we hear. Under around 2 msec, we hear NOTHING.

There, inside this time of around 2 msec to 5 msec [depending on the amount of apsorbtion installed in the room], the R1 ''manage'' to be active or beginning to be. We CANNOT sense nothing or almost nothing inside this sensorial delay.  So the said...real time, is not quite real time, even for sound neither for vision... Just be happy - as me - that the R1 time.

Even when we have less than half back wall (behind the loudspeakers) covered with R1, we have an evidence that using the R1 the acoustic field is ''forced'' to symmetry, or ... the ''expected'' wrong stereo image becomes a wide natural well defined stereo.

In all rooms treated with R1 (even if the walls are partially covered with initially mounted absorptive materials) are in conformity with the EBU tech3276 & 3286 recommendations at the EXCELLENT level and beyond it. In our opinion, what matters most is the resulted room's field timbre & sound dynamics, music's or voice's natural pattern.

Just that being ''deaf'' for a moment (around 2 - 5  msec) is not enough...There are some other ideas (commented by me here) that spatial hearing is inherently nonlinear implying that we might have to consider some nonlinear storage format, which only helps store transients more accurately (the brain's in/out connection with reality). From here thinking to a (perceptual) temporal resolution of an audio system approach tending to infinite (temporally - meaning memory  not frequency domain which - resolution - is distorted from the very tympanum - ''first sound touch''.

Also - a myriads of implication: inherent nonlinearity in hearing (computational models of microcilia!) used to explain difference tones, perception of harmonic/nearharmonic spectra, missing fundamentals - levels of pattern recognition (learned vs. intrinsic) - comodulation of masking release and profile perception as signs of cross frequency band processing at a low level - the consequent refutation of strictly tonotopic place theories of pitch. A ... conclusion?  

What if ALL this non linearity is just another sensorial delay? Lets consider our recording  versus loudspeakers / room interface. When a pure diffused field is created in the room then inside the sensorial delay enters the diffusers actions. Consider and might be 99% true that this sensorial delay is the ''real time'' ( or time ''0'' - zero ) for our hearing.  Mathematically and using the concept of quantum mechanics (because we have a human observer  / consciousness where the loudness versus timbre or spectral envelope are subdued as 'beliefs', and other thoughts are again delayed - Stapp, 1972 ), the absorptive material is adding a zero + something (x) depending on its surface relative to the room dimensions. Saving the World from absorption must be everyone's ''crusade''.

If we define the ideal impulse perception as the one at the moment zero, then , having absorption in the room, we get all the time a ''zero + x'' delay. We know that in music the impulse is the attack time of a note, like the one that we hear very very near a piano or better very near to a drum set, with just a hard played note. The more absorption we have the more far away from the piano / drum we feel. Can we consider R1 as a case solved within the ''mind over mater and back to the mind'' concept ? I think yes. There is no person experiencing the R1's sound and going back to a previous situation.

Non linearity in sound perception might be considered a shifting in all parameters so keeping or succeeding a pristine room acoustic situation helps our brain in less ''computing'' and more musical pleasure. In an absorptive environment he have also pleasure (statistically, for the non connoisseurs) but is the pleasure of LOW - FI ( read Low Fidelity).  Be sure that a decent Hi-Fi system sounds more musical in a proper acoustic environment than a very expensive system in an absorptive one. Being a real music lover is the true answer. We can sense and pleasure the music? then we are gifted creatures..

Why I insist so much about symmetry in the room? Like that we have a field ''ready'' for the original field of the recording, there will be minimal interferences between them. This symmetry is not only a geometrical one. The R1's surface will produce a consonant environment for your recording and room. This consonance or unison of the musical fundamentals / octaves or their harmonics details (exact or even approximate) are continued in our brain as neural-firing coincidence. This is the ideal continuum interface - recording / room / hearing and is the way a musician perceive the music. With the help from the R1's diffused field, your CDs or LPs or movies will sound like the original ones, with their perfection (meaning the reality at the recording's moments and space) or imperfections.  I prefer to expose here this rough series of ideas.

Similar results and ideas but obtained in the laboratory conditions are here. Headphones listening is not exactly similar to real room music listening, but doing such type of research in a room using two loudspeakers, is extremely difficult. Why? Even 1 degree of head movement, change our aural perception. Like that, the statistic repetitivity between the subjects is broken.

Intuitively, the grouped R1 can looks like that, a finite numbers of coupled musical tunning forks as local oscilators, as a demonstration of wave propagation in two-dimensional arrays of scaterers. The detail, the important detail, is in how many directions to be coupled the musical tunning forks and the fact that in the R1's situation, we have two layers of complex coupled forks tied together by the Janus effect.

Besides the WHEN history, we have also a HOW ones. In the project presented below, we have a 4000 Kg of 6 ways of totally horn driven audio system, where we designed two very low frequency of 12 meters long double horn drivers working from 1 to 100 Hz. The whole system, using 50 R1 on the back wall and 24 R1 upon the ceiling has a resolution of +/- 0.25 dB from 5 Hz to 20.000 Hz.

A blend of music lovers dreams with the real high fidelity

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>Important note from the PCT International search report for our patent

 1.  Classification of subject matter and fields searched : IPC 7  G10K11/20   E04B1/84

 2. The documents considered to be relevant for this invention- the Roundffusor1, were all in the ''A'' category [document defining the general state of the art which is not considered to be of particular relevance, having almost nothing in common with a previous art]. There are 3 older patents [1939,1957,1983 , with indications, where appropriate, of the relevant passages, also, not considered to be of particular relevance ] and a sole paper to be open from here. This indicate the almost absolute originality of our invention. The paper is an indication of our predictions that the Roundffusor1 may be used and as Music hall’s ceiling stage reflector or generally in big Music Halls because is the most efficient diffuser on the market, it's diffused field being easily perceived at more than 12 meters from any angle.



About quality and money



The Roundffusor1 may be used in any kind of rooms

Recording studios

Post production studios

Broadcasting studios

Listening rooms

Home theaters

Quality control rooms

CD mastering

Press conference rooms

Film mix and dubbing stages

Music Schools & practice rooms



The unique & efficient room treatment proposal


An example for a room of about 8x6x3 meters. For DO and DON'T situations, please open the FIRST READING page from the main menu.


Room treatments proposal

from many other international companies

White color means an empty wall. In this example, about 10% from the room's total surface (including floor) is covered with 30 grouped Roundffusor1. This solution may be used easily in the recording studio's control rooms. The R1's location must be regarded in a statistical way. The 30 or less required R1 for the 8 x 6 x 3 m situation, may be mounted all, upon one wall's surface or only on the ceiling surface or, as shown, in a combination of both. Of course, the R1's advantages shown below in the recording studios rooms, or live music rooms / halls cases are also valid.



There are differences between where and how to be mounted the R1

A. in rooms for listening music- generally : we have to put grouped R1 only behind de speakers (mainly for electrostatic or with any kind of back radiation speakers) or behind the listening place or on the ceiling if not possible in the previous places. At least 1 meter must be let between the R1's surface and the loudspeakers.


 B. the specific recording studios rooms, Music Halls or TV plateau situations, rooms of any dimensions: many patches of at least 9 (nine) grouped R1 must be periodically / symmetrically mounted if possible on all lateral walls and sometimes on ceiling. If needed, the loudspeakers plays with excellent results.











  the loudspeakers

Black and grey color means various soft & hard acoustical materials and fabrics. This is an almost 100% walls covering instead of about 50% as the latest research indicates and in cases when no serious room resonance is initially predicted or measured.


There are differences between where and how and to be mounted the R1 in rooms for listening music - generally and of any dimensions, and the specific recording studios rooms or TV plateau situations, rooms of any dimensions. 

1. When R1 are used, the reverberation time (RT) will be drastically reduced whatever being the room dimensions and needs. The RT reduction produced by clean diffusing is more important than the one resulted from classical absorption. The RT's reduction when clean diffusers like our R1 are used, have two main advantages: a)  the R1 is a hard, light and non porous material, not needing any further care, and b) even for voluminous rooms as churches and especially closed sport stadiums , the quantity / surface of R1 coverings  have a substantial reduced surface. In plus with the R1, a high level of intelligibility is obtained corroborated with the unique low frequency absorption, both useful for a multipurpose and voluminous hall used for sport activity and for live amplified music. For big music halls like sport venues, opera houses or even churches, this higher level of intelligibility means that the people are able to understand the words, their meaning, not just being exposed to a confuse and enough noisy musical content.

2. For recording studios rooms, or live music rooms / halls of any dimensions for vocal or/and instrumental performances, patches of at least 9 (nine) grouped R1 must be periodically / symmetrically mounted if possible on all lateral walls and sometimes on ceiling. The R1's wood supports may be mounted vertically - for maximum low frequency filtering or horizontally - for a softer low frequency treatment, if such effect is needed. In special situations, using grouped/patches of R1, a combination of supports orientation for each patch may be studied. An homogenous musical field or, an average acoustic potential density in the room's rectangular cross section will be obtained, both, equally perceived by any listener or a measurement tool, everywhere in the room treated with R1.

The room's field being homogenous and the EDT's measured and perceived as being lower than the overall RT60 which is already lowered by the R1's functioning, it is obvious that there is no need for other absorptive materials. The Roundffusor1, being so active, and periodically arranged on the wall's surfaces, dissuades the absorptive materials (ABS) - here is the related paper. You may open as many microphones as you please or need.

We may read from the (ABS) : ''Much research has been performed regarding how the size and arrangement of absorptive materials affect sound absorption. Parkinson1 measured the absorption coefficients of absorptive materials in different patterns and different arrangements. His experiments showed that there is a maximum effective spacing that depends on a wavelength; longer waves appear to have a wider spatial influence. He explained that this is mainly because of diffraction. Sabine/2 also noticed this diffraction effect. He noted that there is some discrepancy between what is predicted based on reverberation assumptions and what is actually measured, and showed that a localized absorption often produces this discrepancy due to diffraction. Chrisler/3 experimentally studied the effect of the size of the sample on the absorption coefficient measurement. His experiments show that the measured absorption coefficient of a small sample is greater than the coefficient of a large sample, and the measured absorption coefficient converges as the sample size increases''.   If you expect a comment from me, well,  the diffusion phenomenon has the absorption's apparent effects but the result is a lower reverberation time and clean sound. The word ''appear'' said it all.

Generally we indicate a minimum of 9 or 12 Roundffusor1(for normal rooms up to 20 square meters, this is the correct R1's number) in situations where the user / listeners are able to discerns between differences in sound quality.  For people presenting an inertia towards deaden or alike room treatments, or because were advised in this way, the number of mounted R1 must be a little bigger. We encountered a situation when a recording studio owner accustomed for many years to listen and record in very high absorptive rooms and then, after about one week in changing to R1 and working there, he acknowledged the benefices of sound clarity and the huge qualitative step, easily recognizable.

Roundffusor1 - the model ''any surface'' or portable

For those of you : undecided, or having peculiar residence problems or non convinced, this is THE solution !

PLEASE NOTE: this model is delivered if you still insist to keep your older/softer acoustical treatment. Already, less and less  people is asking this ...because they understood the real R1's benefits.

So, for those of you decided to acquire our Roundffusor1 but [still] intending to keep the old ''acoustical treatment surfaces'', we provide an improved Roundffusor1 with the same geometry, material and same external dimensions, just about 1 Kg heavier. It can be mounted - wood framed, upon fiberglass fabrics covered, on any kind of rugose / with asperities wall - stone wall, not plain decorative wood panels, etc., or any kind of porous or absorptive foam materials. In this way, cannot be acoustically influenced by the surface upon it is mounted. This model may be used also in trade shows or professional demo rooms, or may be sent to clients who doesn't allow that the R1 be directly mounted on the wall surface.

This model doesn't need any heavy sustaining wood back panel ! More, with the provided on demand or customer's self made wood parts, permitting a logical and easy assembling, you may have a portable grouped Roundffusor1's surface. As the Roundffusor1 standard, the 9 or 12 or 15 grouped portable R1 must be positioned behind the speakers or behind the listening place, always symmetrically towards the source's median axis. The distance between the portable R1 kit to the back wall- just few millimeters. It may be mounted or dismantled in minutes, or if your room permits, with some care, be entirely moved to another place. Once you are convinced that our invention is an useful one, you mount the R1's directly on the wall's surface, having no more acoustical room problems, a resolute situation. And once again, don't forget that your beloved LP's, CD's and DVD's are made in a recording studio and your dedicated room for music must behave similarly. More and more recording studios are made having the Roundffusor1 as a basic , not to say sole acoustical material.

Why not imitate the professionals?   If this seems a commercial trick to you, please go elsewhere...


Some conclusions resulted from R1's practice:

Less absorption on mid and high frequencies represents... MORE MUSIC !

First  conclusion:  The absorption resulted from abusive use of soft porous materials as acoustical treatment is the unfortunate solution of  the bad sound quality in rooms, be voices or music dedicated or both. Generally, a carpet on the floor ( not strictly necessary ), the furniture in your room and your bodies are enough for the required absorption.  

Second conclusion:  The self adaptive bass absorption offered by the R1, removes the harmful dynamic masking effects produced by the low and very low frequencies towards the right of the audio scale. The R1 provides linearity for the low frequency and clean diffusion for the mid and high frequencies, working like an inverse ultra fast automatic wide range digital equalizer, his power supply being the music only. These are facts easy to be perceived and measured. The R1 may be used in any kind of room, of any geometry, the bigger the room is, the more the diffused field is more coherent and musical, with no difference between the live music heard in concerts and your audio system.  

Some other ideas, may be found here  and in conclusion sounds like: '' after all , our ears are almost similar for all of us [ statistically ] : it is the level of your hearing health and mostly, the pleasure of your musical education which will make the difference. R1 it is an important cultural step helping people who loves music, any kind of music, to return to their hobby - and not just buying expensive gear, before  is too late''...The unique solution is here. Sound impressions in rooms were installed : unveils more and more details in the mix, realistic sound stage and instruments location, outstanding voice , instrument quality & musicality, less fatigue at high levels of listening...

Third conclusion: After many R1's installations - for normal or critical listening, the 9 or 12 Roundffusors1 mounted behind the loudspeakers or behind the listening position are enough. But, after mounting the required R1, if you put just one R1 on the lateral wall, in your left and right- symmetrically, near the listening position, one may vary the depth and the height of the perceived sound image and reverberation.

The geometrical center of the grouped Roundffusors will be the center of the sensed height and depth of the perceived diffused field. When mounting the R1's consider to ''tune'' your perceived diffused field in relation with your hearing ability (if you need maximum diffused field, the R1's geometrical center must be at your ears level ).  There must be some 1,5 - 2 meters between your listening position and the R1's surface, the same for the loudspeakers (if R1 are mounted behind the loudspeakers ). Why ? Because the R1's diffusion lobe may be surely sensed at 6-8 meters and more than 12 meters for experienced people.

There is a paper :’’Audibility of "Diffusion" in Room Acoustics Auralization’’ by Rendell R. Torres, Mendel Kleiner -Chalmers Room Acoustics Group, Chalmers University of Technology and Bengt-Inge Dalenback –CATT. This paper is analyzing the fact that ‘’ inaccurate modelling of scattering is a remaining weakness of room acoustics auralization. Part of the reason is that various mathematical models for scattering have not been fully exploited and optimized for rooms. Instead, binaural room impulse responses are currently simulated using approximate, geometrical models and energy-based "diffusion" methods to approximate surface scattering and diffraction. But even with these methods, one has a lack of reliable input data’’.

For those of you able to read, discern, compare and conclude, there is enough similarity between this paper as an idea and the ‘’résumé’’ of my invention’s real results description, all this paper being a kind of prediction /confirmation of what MAY be possible.

Please note, the huge difference between predictions, simulations and laboratory aural tests and the real thing in real life with clients having their own music and own aural perceptions. I can run myself any kind of aural test with real people, in their very rooms, with their cheap, expensive or huge priced audio systems [see at ''STUDIOS'' - best application].

All the test to be done in rooms treated with Roundffusor1, will obtain a safety 99,9% positive acceptance. Many of my friends – all of my clients became my friends, are telling me their own stories about how the R1 helped them to re-gain and re-enjoy the almost lost music listening pleasure [selling, buying or exchanging the audio gear, without fixing the room problems].

And don’t forget that real music begin there were the recording is made, continue in each ones real , specific room [ now treated with R1] , specific room being ‘’driven’’ by specific loudspeakers, which speakers plays as low as 15-or 17 Hz or even lower for some subwoofers [ computer simulation ''stops'' at some 125 Hz ]. The lower frequencies the loudspeakers plays, so lower and even lower than that, the very room ‘’play’’ also – in the named ‘’infrasound’’ zone. There is no way to solve simultaneously all this problems with the acoustical materials designed until now.

Learning about our USEFUL SOLUTION - The Roundffusor1, probably you understood that it is working adaptively down to some 5 Hz, so your room treated with R1, are SAFE for all spectral situations and for all kind of audio systems – from the cheapest to the most expensive ones. I've designed the velvet like covered R1 just to solve the horn speakers directivity problem. Please bear in mind that all kind of electrostatic speakers needs unconditionally that the wall behind them have be covered with R1 , on a surface, geometrically, similar with the surface ''seen'' by the loudspeakers, from their left to the right. The wider the distance between those loudspeakers , so much the surface covered with R1 on the back wall, behind the loudspeakers.  

At some Forums on the Internet, a wide and open discussion opened around R1. Many people tends to understand part of the explanations given here and some ( for strange reasons ) asks for more. We don't use paid articles or virtual results. All this site - regarding the R1- is just a continuous description of what really does the R1. The R1 is an adaptable low and very low frequency absorber so for this thing , each measurement is specific to a specific room geometry / number of mounted R1 and the kind/position and quality of the audio system. So the absorption curves will be each time a specific measurement not possible to be indicated for another setup, even slightly different.

Even the ''old design'' of materials dealing with low frequencies doesn't behave the same in different conditions. The R1 works to near perfection only grouped mounted, so the bigger the room the more R1 you need, just for one wall (usually). Because the R1 works grouped, their empty column's linear dimensions are a whole or a fraction of the wavelengths of the spectral source and the air inside each columns resonate accordingly to the source spectrum and energy, a dynamic situation. There are complex phenomenon between the R1's back Helmholtz resonator function and the very active frontal diffusion one. Special and sophisticated mathematics or practical and superb results ?

...   In 1970 Alvin Toffler, noted technologist and futurist, argued that the acceleration of technological and social change was likely to challenge the capacity of both individuals and institutions to understand and to adapt to it.  ... Our ability to handle simultaneous complexity is governed by what cognitive scientists call "fluid intelligence," commonly defined as the ability to find meaning in confusion and to solve new problems. But this process will inevitably have limits. Eventually, we'll hit a ceiling in the ways in which we can improve our fluid intelligence naturally. At that point, we'll face a hard choice: make major changes to our work and social cultures, so as to reduce the degree of simultaneous attention-grabbing activity; or develop augmentation systems that enhance our natural fluid intelligence by recognizing, from moment to moment, what needs our actual focus, and what can be handled by proxies. The wise choice would be the first one. It should come as no surprise, then, that I suspect that we'll do the second (from Open the future by Jamais Cascio ) or, with enough minds, all tomorrows are visible.

With the Roundffusor1 many acoustical ''squared ideas'' becomes obsolete. Why not put the loudspeakers half way between listening position and the opposite wall ? In this area the direct and the reverberant field are somehow blended.  In real life, in a ''spark'' of 25-100 millisecond what is going to happen will happen.

It is the time that our ( experimented and perhaps educated) hearing system ''concludes'' and we understand the sense and meaning of those precious words defining the sound quality. If this audio field is not a pleasant one, nothing will save you - even the most expensive gear , but the acoustics and ONLY the Roundffusor1!  In applied acoustics, this ONLY is rare...  


By < sound insulation > we understand to not disturb our neighbors or be disturbed by them – this being ‘’performed’’ by putting between ‘’us’’ and ‘’them’’ enough ‘’concrete’’ distance, meaning one or more parallel solid walls or much wider ‘’patched’’ porous materials, but wide is anything more than 1-2 meters or more in order to attenuate AND the low frequency disturbance. Even technically educated people confuse interior room acoustics with sound insulation.  To be precise, if you mismatch the porous ‘’sound insulation’’ with ‘’room acoustics’’ the ‘’best’’ result will be an insufficient sound insulation and a very bad quality room’s sound field – a muddy and without clear / natural midrange and high frequency spectrum, I repeat – IN THE ROOM.

  The Roundffusor1 introduces a new concept


This means that your listening or home  cinema room doesn't need to look like a recording studio or an architecturally, aesthetically & heavy absorption charged villa's suite, which may be the road to indulge yourselves in a little bit or more luxury, but surely not the way to the ideal sound.

Roundffusor1's mounting instructions


How to integrate the Roundffusor1 into a typical false ceiling



An example for a matrix of 3 x 3 R1's, meaning 9 ROUNDFFUSOR1. We have 4 parallel wood rails / supports, for 3 rows of Roundffusors. Each wood support is 58 x 3 = 174 cm long. Each diffuser is mounted upon 2 lateral supports, and all diffusers are mounted in parallel rows, vertically or horizontally relative to the floor, if to be put on the back wall. You need 1 screw for each, meaning 2 screws / Roundffusor1.

But  each  second  support  is  common for 3 neighbor diffusers - because they are mounted in rows, so in fact 3 diffusers in a row, needs only 6 screws, 6 diffusers needs 9 screws and all 9 needs, you guess, only 12 screws. If you want to be more secure, you put more screws. If mounted on a wood surface, nails, are enough. Maybe you think '' big'' , but each wood rail is a section of [30x30 mm, of a ''T'' profile] and some 174 cm long for rows of 3 Roundffusors.

All 9 Roundffusors standard weights only 9 x 2 Kg= 18 Kg, so no need to worry about. The way  they are mounted makes them to behave like very heavy plastic, so no resonance will results, if you are afraid of it, and NO SOUND COLORATION. Generally, for rooms of less than 25 square meters, the nine or twelve Roundffusors on the back wall - opposite to the loudspeakers place, or just behind the speakers, are enough for a first good impression.


Few testimonials

...'' we made listening tests some 10 years ago on scale model diffusers which showed that spherical diffusers were superior in sound quality '' PhD M. Kleiner, Professor - Director, Program in Architectural Acoustics School of Architecture Rensselaer Polytechnic Institute , Director, Chalmers Room Acoustics Group School of Civil and Environmental Engineering Chalmers University of Technology, Gothenburg, Sweden.

...  and my friend from Russia said : ''Dear  Zainea, Thanks for your message of 22 August 2002. You seem to do very interesting and important practical work in acoustics. In spite of I am more theoretician, I can feel the key essence and advantage of what you have already achieved in your research. ‘’ Russian Professor M. A. Sumbatyan

... '' In simple words it cleans the lower and diffuses the higher frequencies and the result is fantastic music. I have installed 15 pieces in my room and still I can’t believe the performance and the change that have been occurred''. A distinguished Greek private client  

... '' Congratulations for the advertisement, the R1 is the best. The 5X3 R1 is at last on the wall. The effect is wonderful. The nasal sound disappeared because of which I could not increase the volume of the sound up till now. The room is quieter; I can listen loudly and softly too without having anything disturbing. The walls disappeared. A lot of information emerged which I have not heard yet. The sound picture is more colour, it received life. The starting and stopping of the voice of the instruments is real now. The beginning and the end of the bass is correct at last, it does not running around the room. Everything is on the right place. A miracle happened. Congratulations. I will send you the pictures. Best regards, Sándor''. From Tamás Sandor, owner and State Hungarian Philharmonic member, Double Reed Co.


Important professional links

 MIX Magazine on line: Acoustic materials 2005-guide to new professional acoustic materials for the studio

 MIX Magazine on line  for the AES  NYC 05 


Roundffusor1's published, independent tests, interviews, all in Greek


'Hxos-Eikona'': R1's Test

AV Pro's article: R1's Test

Radio-Link's article: R1's Test 

Radio-Link - Zainea Liviu Interview


United States Patent 7,261,182 -  Zainea Liviu Nikolae.

Title: Wide band sound diffuser with self regulated low frequency absorption and methods of mounting


Zainea Liviu at the University of Patra / Greece - The Roundffusor's presentation




Hearing is believing !


about brain perception  (adapted for audio...:)

many audio dealers will ''show'' you that A and B are different colors ...

with Roundffusor1  you will hear the difference between electronics...








in fact, A and B are of the same color (5)

so, where is the truth ?  little help  here ... or... here  



Music: The Art of Listening





Company address

 Mr. Zainea Liviu Nikolae / ESR,  14 Peresiadou street, TK11141 Athens, Greece   

 Communications data

Email:    Tel/Fax: 0030 210 20 27 191    Mobile: 0030 693 66 07 321

Skype: zainea.liviu

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