The argument for/against room treatment

[sbnx]

The effective frequency bandwidth of a fibrous absorber is primarily a function of the depth of the absorber and to a lesser degree, the angle of incidence of the incoming sound source to the absorber. A half inch thick carpet made from ideal materials (open weave jute backing, no plastic, wool fibers) will only act upon only the uppermost audible frequencies and thus not be very useful. You will have created a narrowband tone control which absorbs the frequencies which impart a sense of airiness to a recording. I want to at least absorb down to the 5kHz range to kill the potential for a hashy, harsh slap echo between floor and ceiling. So I'll place a double thickness of 1/2" felt underpad beneath to create an overall depth of 1.5" to broaden the absorption bandwidth usefully.

Here is the thing as I see it. Unless you are using a loudspeaker like a line array or horn based loudspeaker which is highly directional at mid and high frequencies, the primary floor reflection is a problem for all of us. You may be blessed with a room with high ceilings and the space to pull the loudspeakers out far away from the walls, far enough that primary wall and ceiling reflections are outside of the problematic 6ms range. But if you use any conventional wide dispersion loudspeaker design, the floor reflection will inevitably arrive in less than 6ms and therefore be a problem. If you use a multi-way loudspeaker the problem will be exacerbated. Your speaker's smooth frequency and phase behavior doesn't stand up outside of a pretty narrow +/- 15 degree vertical window due to lobing effects in the crossover between drivers. So that early floor reflection will have a jagged frequency response which will then recombine with the direct sound in an even more problematic fashion.

If it weren't so impractical to implement, I would place a pair of 3-4' square and 6" deep broadband absorbers at the primary floor reflections. I know a few other keen members here besides me have experimented with this. I suppose in a perfect world an all-out, ground-up, custom built room could incorporate large steel gratings in the floor beneath the carpet. These gratings would be centered in the anticipated vicinity of the primary floor reflections. Then you could place the deep broadband absorbers below floor level. You would have the performance benefit without the physical or aesthetic obstruction of a surface mounted absorber.

100% agree with all of this. I read a paper a few years ago from either AES or ASA that showed the results of various types and thicknesses of carpets. Normal or even wool carpet simply kills reflections above 10 KHz.

If you go back in this thread I posted about using an absorber on the floor. I bought a large canvas bean bag cover from Amazon and filled it with sheaded demin insulation. The effect is quite obvious -- Much less smearing in the vocal range. Even non-audiophiles can pick this up an an A-B test. I posted some REW data on this in a thread I started called "Help with floor bounce diffuser" if you are interested. You could use a couple custom made ottomans to accomplish the same thing and also make it look nice. I thought about building a couple for myself.

I had also thought about the in-floor "pit". The trouble comes in that you don't know exactly where the listening position and speakers are going to end up until you build the room. Very hard to do after everything is built.

The main reason I hate carpet is that it is much harder to get accurate speaker position than on a hard surface. But looks like Ron will overcome this by not carpeting the area the speakers sit in.

 

[sbo6]

Indeed needing some form of room treatment is the long-standing rumor. From a common sensical perspective, I'd imagine that walls, floors, and ceilings will interact or "interfere" with any sound generated live or playback. It is the nature of sound and acousics. Whether it be a football stadium, a large gymnasium, a 2-car garage, or a walk-in-closet.

I'm compelled to ask those who think room acoustic treatments / custom rooms as a necessity. Is it at all possible that room acoustic treatments in general don't actually make a playback system hence its playback presentation more musical (how could they?), but rather they only make an already less-than-pleasing playback presentation less fatiguing / more tolerable / more pleasing? That's my hunch. And if possible, might not such a strategy be kinda' bass ackwards?

I find it interesting that in this hobby with the science / data group on one side and the trust your ears camp on the other side that this is (to be frank) even a disagreement. Room treatment has been scientifically understood and proven to be effective over 80 years ago. Concepts and products adopted from concert halls and recording studios have been in use in 2 channel and surround sound home rooms for decades. And with a few simple tools like REW + a mic you can measure and see the benefits. Net - there's no rumor, there's a plethora of science and data available that's easily measured. And articles and videos abound proving the benefits. Note: This is irrespective of your playback system quality (or lack thereof).

Can room acoustic treatments make a playback system and hence its playback presentation more musical? Absolutely - via attenuating low frequency peaks and reducing the decay time yields more natural bass and avoids clouding the mids and highs. How about attenuating first reflections that would otherwise arrive <= 10 msec after the primary source which our ear brain perceive as a lack of clarity. And there are many more examples.

 

[microstrip]

I find it interesting that in this hobby with the science / data group on one side and the trust your ears camp on the other side that this is (to be frank) even a disagreement. Room treatment has been scientifically understood and proven to be effective over 80 years ago. Concepts and products adopted from concert halls and recording studios have been in use in 2 channel and surround sound home rooms for decades. And with a few simple tools like REW + a mic you can measure and see the benefits. Net - there's no rumor, there's a plethora of science and data available that's easily measured. And articles and videos abound proving the benefits. Note: This is irrespective of your playback system quality (or lack thereof).

Can room acoustic treatments make a playback system and hence its playback presentation more musical? Absolutely - via attenuating low frequency peaks and reducing the decay time yields more natural bass and avoids clouding the mids and highs. How about attenuating first reflections that would otherwise arrive <= 10 msec after the primary source which our ear brain perceive as a lack of clarity. And there are many more examples.

No doubt that acoustic treatment can improve a room. The problem is that there is no cookbook that tells users exactly what to do, and according to our members repports it seems that most times it results in more harm than good.

 

[sbo6]

No doubt that acoustic treatment can improve a room. The problem is that there is no cookbook that tells users exactly what to do, and according to our members repports it seems that most times it results in more harm than good.

IME I've never heard a room without treatment get worse with some treatment. However, I've heard rooms with some treatment get worse with additional and / or replacement treatment. Most rooms sound pretty bad without minimal treatment especially with higher quality systems.

 

[Elliot G.]

Its not the paint brush its the Artist. No offense to the "members" reports but it requires knowledge on how to use the room treatment products. In most of the cases I have seen the axiom seems to be " if one is good 5 is better"
We live in a world full of "experts" and these "experts" are used mostly to make the point of the writer.
If you find someone or somewhere that has great sound then perhaps you should trust them to help if you don't hear then why believe ???
People do the same with reviews, it has become a permission slip to enjoy what they have purchased or want to purchase.
Its common sense that if I read a restaurant review by X and I go there and its awful I am not likely to go to another of his suggestions. The point is that since very few actually get to hear what the reviewer is you should take this information as a starting point not the facts!

 

[sbnx]

The point is that since very few actually get to hear what the reviewer is you should take this information as a starting point not the facts!

Amen to that. Especially true for reviewers that are constantly claiming something is "The best I have ever heard".

 

[Elliot G.]

Amen to that. Especially true for reviewers that are constantly claiming something is "The best I have ever heard".

I don't have a problem with that statement only that it is a singular point in time with no real meaning. What else have they heard? where? was it in their room and reference system? Do they even have one of those? Did they choose it or did they get stuff because it needed to be reviewed by someone?
I was stunned by some of those who requested our speakers for review that they had none of these things and in fact didn't really have a listening room.
I don't think I would hire a plumber with the same knowledge upfront, or electrician, or any other profession that didn't have the proper tools to do the job. One has to have the tools of the trade in order to do the job along with the knowledge and experience. Listeners don't have to they want to listen to music and enjoy what they have. If they want to get serious they too need to meet some objectives in order to get the best out of what they own. To them its a choice not a prerequisite to doing an "experts" job.
There are some that have lots of tools and lots of experience and there are others that start a YouTube channel or a website because they can PERIOD. My suggestion is be careful who you select as a tour guide it could be a long strange trip if you choose wrong.

 

[rsrzr]

you cannot have a reference system without treating the room 1st. Speaker placement will only get you part of the way there. No speaker placement will get rid of 1st reflection issues or what issues corners cause unless your room is outside, then you have other issues.

 

[cal3713]

Not completely on topic, but I thought people in here might be interested in this new sound isolation screw for drywall I just ran into...

https://newatlas.com/good-thinking/spring-loaded-sound-screw-soundproofing/

 

[Carlos269]

you cannot have a reference system without treating the room 1st. Speaker placement will only get you part of the way there. No speaker placement will get rid of 1st reflection issues or what issues corners cause unless your room is outside, then you have other issues.

Care to explain and enlighten on the criteria and exactly how someone goes about “treating the room 1st” without taking into account and factoring in the excitation source? And further to that, how those established room treatments respond to changes in excitation characteristics, wave-front polar and 3-dimensional dispersion patterns, frequency response, position of sound source from the room boundaries, room furnishings and outfitting, and so on? And how does one validate that the design specifications, assuming that they are specified to begin with, have been achieved?

Just going through the mental exercise will enlighten you that comments like that roll of the tongue with ease but are far more complex to evaluate and execute with any form of scientific and engineering precision in any type of universal way.

Back in the late 70’s Bruel & Kjaer published the ultimate reference on Architectural Acoustics. It provides good practices and guidelines for the design of rooms for music, but even it states:

“It is much more difficult to state the criteria for good listening conditions for music than for speech because aesthetic and emotional judgments are involved. The criteria are almost totally subjective making them very difficult to define and often impossible to measure. The designs of rooms for music is therefore as much an art as a science.”

This pursuit of the ideal listening room is the proverbial rabbit hole. Besides the obvious need for isolation from exterior noises and eliminating imparted resonances, what defines and makes one environment better than another? What is it about bespoke listening rooms that makes them more ideal than domestic rooms? I’m looking for substance here not aesthetics.

 

[Lagonda]

Or you can just pile up equipment in every free inch of the room, and thereby totally take the room out of the equation !

 

[Cellcbern]

Care to explain and enlighten on the criteria and exactly how someone goes about “treating the room 1st” without taking into account and factoring in the excitation source? And further to that, how those established room treatments respond to changes in excitation characteristics, wave-front polar and 3-dimensional dispersion patterns, frequency response, position of sound source from the room boundaries, room furnishings and outfitting, and so on? And how does one validate that the design specifications, assuming that they are specified to begin with, have been achieved?

Just going through the mental exercise will enlighten you that comments like that roll of the tongue with ease but are far more complex to evaluate and execute with any form of scientific and engineering precision in any type of universal way.

Back in the late 70’s Bruel & Kjaer published the ultimate reference on Architectural Acoustics. It provides good practices and guidelines for the design of rooms for music, but even it states:

“It is much more difficult to state the criteria for good listening conditions for music than for speech because aesthetic and emotional judgments are involved. The criteria are almost totally subjective making them very difficult to define and often impossible to measure. The designs of rooms for music is therefore as much an art as a science.”

This pursuit of the ideal listening room is the proverbial rabbit hole. Besides the obvious need for isolation from exterior noises and eliminating imparted resonances, what defines and makes one environment better than another? What is it about bespoke listening rooms that makes them more ideal than domestic rooms? I’m looking for substance here not aesthetics.

Achieving good acoustical room treatment results has gotten easier than it used to be. Conventional room treatment requires lots of measurements because different types and thicknesses of acoustical devices are required to target different frequency ranges. Yet unless I am mistaken most if not all acoustical measurements are of reflected sound, and the most troublesome room mode issues arise from sound waves bouncing between the front and rear walls. What if there was a thin panel that eliminated reflections across the whole frequency spectrum? DHDI's "Zero Reflection" technology doesn't absorb, diffuse, or trap sound waves. Rather it "deconstructs" them before a reflected sound wave can form by bouncing the air that carries the sound off of many thousands of non-parallel surfaces. I tested what at first seemed to be outlandish claims and documented my experiences on this forum:

(https://www.whatsbestforum.com/threads/trying-the-zr-acoustics-panels.31846/).

The ZR Acoustics panels worked as advertised and proved markedly superior to all of the conventional treatments I've tried (e.g, RPG BAD, GIK, ASC, etc.). This was all done using my educated ears - without taking any measurements. A colleague who is an acoustical engineer by training and profession also tested the ZR panels and was very impressed with them.

Several reviewers have had similar results:

From Stereophile: 4. Delta H Design Inc. ZR Acoustics panels: $299 and up - Delta H Design Inc. (DHDI) is an architecture firm and acoustics consultancy in Marina del Rey, California. Their audacious claims for their ZR Acoustics room treatments (patent pending) include that the acoustical panels, which range in thickness from 3/4" to about 4", can control sound in a range from 1Hz all the way up to three octaves above the range of human hearing, ca 160kHz.

Obviously, such claims fly in the face of conventional "quarter-wave theory." Designer-inventor Hanson Hsu says that his mission is to drag architectural acoustics away from the Newtonian billiard-ball model and base it instead on quantum and Mandelbrotian realities. DHDI's technique for radically increasing the number of nonparallel surfaces in a panel "employs fractal and tessellation mathematics hybridized with chaos theory."

Chaos is not anarchy—ie, that the natural universe has no laws. In this context, chaos theory means—as shown by Henri Poincaré's brilliant failure to solve the three-body problem (footnote 1)—that what may appear to be completely random is instead merely bafflingly nonlinear.

DHDI sent me two 24" by 24" by 1.25" ZR Micro panels ($599 each) to go behind my speakers, and three 20" by 40" by 0.75" ZR Sample Rate 8 Bit panels ($299 each) to go between and above the speakers (total: $2095 plus shipping). Hanson Hsu thought those the bare minimum needed to appreciably improve my listening room's sound.

Hsu says that DHDI's design goal is a sound that is "transparent, organic, and musical." In my room, the ZRs accomplished all that in spades. To boil it down to one adjective, the sound was richer. Mobile Fidelity's amazing SACD remastering of Dire Straits' Brothers in Arms converted even a hardened room-treatment agnostic. I was very impressed. A review is in the works. (www.deltahdesign.com)

The Fifth Element #90

As a film title, Quantizing Hanson Hsu might not rank up there with Kissing Jessica Stein, but we work with what we have to work with. Hanson Hsu is the principal designer at Delta H Design, Inc., an acoustics and architecture firm based in Marina del Rey, California. Though he dabbles in some...

www.stereophile.com

https://sonicscoop.com/2012/12/12/delta-h-designs-zr-acoustics-removing-the-room-from-the-room/

Alan Meyerson Adds DHDI ZR Acoustics in Hans Zimmer's Facility

Delta H Design Inc. (DHDI) in Marina Del Rey, Calif., the leader in Quantum Acoustics, announces the use of ZR Acoustics Quantum Devices in Alan Meyerson’s premier music studio at Hans Zimmer’s Remote Control facility in Santa Monica. Two SR8+’s quantize the first reflections behind both the...

www.mixonline.com

The Client List:

Delta H Design

Check out SFSCS.org

deltahdesign.com

I still have conventional absorbers and combination panels on the side walls and ceiling because the ZR panels are expensive, but with no significant reflections off of the front and rear walls my listening room sounds better than I could have imagined.

 

[Cellcbern]

My deployment of ZR Acoustics panels:

 

[Carlos269]

Achieving good acoustical room treatment results has gotten easier than it used to be. Conventional room treatment requires lots of measurements because different types and thicknesses of acoustical devices are required to target different frequency ranges. Yet unless I am mistaken most if not all acoustical measurements are of reflected sound, and the most troublesome room mode issues arise from sound waves bouncing between the front and rear walls. What if there was a thin panel that eliminated reflections across the whole frequency spectrum? DHDI's "Zero Reflection" technology doesn't absorb, diffuse, or trap sound waves. Rather it "deconstructs" them before a reflected sound wave can form by bouncing the air that carries the sound off of many thousands of non-parallel surfaces. I tested what at first seemed to be outlandish claims and documented my experiences on this forum:

(https://www.whatsbestforum.com/threads/trying-the-zr-acoustics-panels.31846/).

The ZR Acoustics panels worked as advertised and proved markedly superior to all of the conventional treatments I've tried (e.g, RPG BAD, GIK, ASC, etc.). This was all done using my educated ears - without taking any measurements. A colleague who is an acoustical engineer by training and profession also tested the ZR panels and was very impressed with them.

Several reviewers have had similar results:

From Stereophile: 4. Delta H Design Inc. ZR Acoustics panels: $299 and up - Delta H Design Inc. (DHDI) is an architecture firm and acoustics consultancy in Marina del Rey, California. Their audacious claims for their ZR Acoustics room treatments (patent pending) include that the acoustical panels, which range in thickness from 3/4" to about 4", can control sound in a range from 1Hz all the way up to three octaves above the range of human hearing, ca 160kHz.

Obviously, such claims fly in the face of conventional "quarter-wave theory." Designer-inventor Hanson Hsu says that his mission is to drag architectural acoustics away from the Newtonian billiard-ball model and base it instead on quantum and Mandelbrotian realities. DHDI's technique for radically increasing the number of nonparallel surfaces in a panel "employs fractal and tessellation mathematics hybridized with chaos theory."

Chaos is not anarchy—ie, that the natural universe has no laws. In this context, chaos theory means—as shown by Henri Poincaré's brilliant failure to solve the three-body problem (footnote 1)—that what may appear to be completely random is instead merely bafflingly nonlinear.

DHDI sent me two 24" by 24" by 1.25" ZR Micro panels ($599 each) to go behind my speakers, and three 20" by 40" by 0.75" ZR Sample Rate 8 Bit panels ($299 each) to go between and above the speakers (total: $2095 plus shipping). Hanson Hsu thought those the bare minimum needed to appreciably improve my listening room's sound.

Hsu says that DHDI's design goal is a sound that is "transparent, organic, and musical." In my room, the ZRs accomplished all that in spades. To boil it down to one adjective, the sound was richer. Mobile Fidelity's amazing SACD remastering of Dire Straits' Brothers in Arms converted even a hardened room-treatment agnostic. I was very impressed. A review is in the works. (www.deltahdesign.com)

The Fifth Element #90

As a film title, Quantizing Hanson Hsu might not rank up there with Kissing Jessica Stein, but we work with what we have to work with. Hanson Hsu is the principal designer at Delta H Design, Inc., an acoustics and architecture firm based in Marina del Rey, California. Though he dabbles in some...

www.stereophile.com

https://sonicscoop.com/2012/12/12/delta-h-designs-zr-acoustics-removing-the-room-from-the-room/

Alan Meyerson Adds DHDI ZR Acoustics in Hans Zimmer's Facility

Delta H Design Inc. (DHDI) in Marina Del Rey, Calif., the leader in Quantum Acoustics, announces the use of ZR Acoustics Quantum Devices in Alan Meyerson’s premier music studio at Hans Zimmer’s Remote Control facility in Santa Monica. Two SR8+’s quantize the first reflections behind both the...

www.mixonline.com

The Client List:

Delta H Design

Check out SFSCS.org

deltahdesign.com

I still have conventional absorbers and combination panels on the side walls and ceiling because the ZR panels are expensive, but with no significant reflections off of the front and rear walls my listening room sounds better than I could have imagined.

The technological advances are there but the original question remains, where do you apply it and to what extend? The science has been there since long ago on how to build anechoic chambers. Some say treat the area of first reflection, but doesn’t that location change with the loudspeaker transducers traveling waves’ propagation pattern and distance of the source from the room boundaries?

Suppose one wants to implement this new material that “deconstructs” the coincident sound waves, where does one apply it and when is it enough, too much or not enough? I saw the pictures of your room and I’m incredulous to believe that you have no contributions from the front and rear walls. If you cover every inch of the walls, ceiling and floors with this material that “deconstructs” the coincident sound waves, have you created a dead room or anechoic chamber?

Great modeling software do exist today for analyzing loudspeaker systems response and room acoustics, my favorite one is the Multiphysics software tool based on Finite Elements Methods, the Acoustics module of COMSOL Compiler.

The science and engineering is there, and it is very easy to create anechoic chambers and reverberation chambers but how do you define, specify and agree on a universal in between? And this is the crux of the matter.

 

[morricab]

Or you can just pile up equipment in every free inch of the room, and thereby totally take the room out of the equation !

The preferred choice of audiophiles everywhere!! Not that wives often let them...

 

[cal3713]

DHDI's "Zero Reflection" technology doesn't absorb, diffuse, or trap sound waves. Rather it "deconstructs" them before a reflected sound wave can form by bouncing the air that carries the sound off of many thousands of non-parallel surfaces.

I don't understand how this is different then diffusion. Can you elaborate?

 

[Cellcbern]

The technological advances are there but the original question remains, where do you apply it and to what extend? The science has been there since long ago on how to build anechoic chambers. Some say treat the area of first reflection, but doesn’t that location change with the loudspeaker transducers traveling waves’ propagation pattern and distance of the source from the room boundaries?

Suppose one wants to implement this new material that “deconstructs” the coincident sound waves, where does one apply it and when is it enough, too much or not enough? I saw the pictures of your room and I’m incredulous to believe that you have no contributions from the front and rear walls. If you cover every inch of the walls, ceiling and floors with this material that “deconstructs” the coincident sound waves, have you created a dead room or anechoic chamber?

Great modeling software do exist today for analyzing loudspeaker systems response and room acoustics, my favorite one is the Multiphysics software tool based on Finite Elements Methods, the Acoustics module of COMSOL Compiler.

The science and engineering is there, and it is very easy to create anechoic chambers and reverberation chambers but how do you define, specify and agree on a universal in between? And this is the crux of the matter.

First of all the ZR panels eliminate or dramatically reduce the reflections without creating an anechoic chamber. Unike conventional absorbers the room never sounds dead. Maybe they have a mild diffusive effect - I don't know, but I did extensive direct listening comparisons between GIK absorbers/RPG combination panels and the ZR panels on the wall behind my listening seat. All reduced or eliminated reflections but the GIK absorbers created a dead acoustic - the ZR panels did not. The BAD panels didn't eliminate enough of the reflected sound. This is pretty straightforward - you have reflective surfaces and you cover enough of them with reflection eliminating panels to eliminate room modes, smearing, etc. What is there to model if you aren't targeting specific frequency ranges? DHDI says that all of their research and experience in the pro audio space led them to conclude that the most important wall to treat was the wall behind the speakers. If you push your speakers right up against the wall /panels as they recommend (and I did) you can start with a relatively small amount of square footage and add more. In my listening room just 16 sf of ZR panels behind the speakers made a big improvement over 24 sf of Gik absorbers, RPG BAD panels, and combinations thereof. I also got rid of my ASC tube traps. What strikes you with even 16 sf is an unprecedented increase in clarity. John Marks of Stereophile documents a significant improvement in his listening room (Fifth Element - #'s 88 and 90 - links above) with 24 sf. No modelling or measurements were done. DHDI recommends that you cover at least 50% of a wall's surface. My coverage on the front and rear walls now exceeds that and the sound quality is incredible. Note that my WBF thread "Trying the ZR Acoustics Panels" features photos showing the progression from the initial 16 sf behind the speakers to what I have now. Adding more ZR panels might yield further improvements but I have stopped for now because of the cost.

 

[Cellcbern]

I don't understand how this is different then diffusion. Can you elaborate?

Diffusors scatter the sound waves and have to be tailored and targeted to specific frequency ranges and room dimmensions. ZR Acoustics panels prevent reflected sound waves from forming ( at a molecular level according to DHDI) by bouncing the air off of many thousands of non-parallel surfaces per square foot of panel, and work at all frequencies.

 

[microstrip]

Diffusors scatter the sound waves and have to be tailored and targeted to specific frequency ranges and room dimmensions. ZR Acoustics panels prevent reflected sound waves from forming ( at a molecular level according to DHDI) by bouncing the air off of many thousands of non-parallel surfaces per square foot of panel, and work at all frequencies.

Do you have any acoustic measurements to substantiate such claims?

 

[dcathro]

Diffusors scatter the sound waves and have to be tailored and targeted to specific frequency ranges and room dimmensions. ZR Acoustics panels prevent reflected sound waves from forming ( at a molecular level according to DHDI) by bouncing the air off of many thousands of non-parallel surfaces per square foot of panel, and work at all frequencies.

Wow, that must have taken the marketing guys a while to think up.

By the way, from your photos, your room looks way over damped (too much treatment). Did you have someone treat the room or do it yourself?