Is there a consensus on what makes a good (or ideal) listening room? A dead room (or anaechoic chamber), or a big live room (a concert hall)?

I thought the "gold standard" was to have a system that you could set-up in the concert hall and have it sound exactly like the live orchestra.... I thought the ideal was to have a good system and a concert hall in your house.

But, the following from the "room treatment" thread got me wondering...


Is the "audiophile consensus" in favor of an anechoic chamber? Is the ideal goal of "room treatment" to kill ALL reflections?


Personally I prefer a large "live" room (larger than my living room). My living room is pretty average (carpeting, etc.) and is fairly "dead". But, I occasionally do DJ work and I've had my speakers in a "dance hall" a few times, and they sound much better (to me) in a large reverberant space. (Yeah, my speakers are "too big" for my living room. ) Of course, the music is louder in the dance hall which adds another variable.... There's something about small rooms that makes me prefer lower volume. (Plus, I have "thin walls" and nearby neighbors.)

To me, the amount of reverb that sounds great in a large space seems unnatural in my living room, especially if the (artificial or recorded) reverb is coming from 2 stereo speakers. With surround sound (i.e. Pro Logic soundfields) I like a little more reverb. But again, the amount of reverb that sounds great in a dance hall (or concert hall) is too much for my living room (in my opinion).

I suppose the worst situation is a small reverberant room? But, maybe a small reverberant room would be OK if had the right shape?

BTW - I mostly listen to studio-produced rock, so obviously any reverb in the recording is going to be artificial (no concert hall). Still... IMHO a Fleetwood Mac CD is going to sound better played-back in a concert hall, than in an anechoic chamber.

No.
"Good" and "Ideal" are going to be subjective.
Consider also when one listens, what is heard is a combination of the acoustic sources and the room, interacting. You have to look at both.

cheers,

AJ

Broadly yes. It is expressed primarily as target reverberation times in a few frequency bands but there are one or two other considerations like reducing early reflection paths and avoiding large time gaps with no reflections in large rooms. However, the target reverberation times vary significantly depending on the use of the room (speech, live music, recorded 2 channel music, recorded multi-channel music,...). A brief google will throw up loads of these targets specified by various bodies and differing only slightly in value.

An anechoic room is not normally desirable for stereo and will sound a bit odd. A bit like headphones if you can set aside the in-head business, clear and precise but unnatural because the reverberation the brain is used to hearing is not there or is not right depending on what is on the recording. On the other hand, a significantly deader room is desirable for multi-channel audio where a lot more of the reverberation is in the surround speakers. But live music generally benefits from a more reverberant room. Etc...

There is a thesis of Wegemann, describing the reverberation of the playback room remain hardly disturbing as long as the recording room was more reverberant.

But by my opinion we cannot simplify the problem onto reverberation. The reverberation tail provide important informations regarding the recording room properties, but its spatial distribution is less important regarding perception.
On the other hand time and direction regarding the first reflections is substantially. Such reflections hit the listener in the recording room from very distributed starting points, behold as mirror sources behind the recording room walls.

If we damping dead the playback room, those reflections cannot produce outside the loudspeaker anlignment. The reproduction becomes boring, reduced to the horizontal level of the Loudspeakers, without the "acoustical attractions", which deliver reflections from directions far beyond the loudspeaker base.


The " WFS-Holophony" would provide such possibility for restore all reflections correctly, unfortunately doesn`t exist a more simple way.

An anechoic chamber would be an awful place to listen to music. We are used to hearing music as a component of both the direct and reflected sound. Room acoustic treatments are there to control - not completely eliminate - those reflected components.

This is why room treatments are usually positioned in key places (bass traps at the points where wall meets wall, ceiling or floor, absorption in the first reflection points, and either absorption or diffraction behind the listener), but not everywhere.

Audiophiles (those who get past the obsession with micro-managing their equipment and nothing else) tend to use bass traps in the corners behind the speakers, absorption on the first-reflection points on the side walls and either absorption or diffusion on the front and rear wall, but not much else. I think the basic idea is to create a 'live' end (where the listener sits) with less treatment and a 'dead' one (where the speakers are placed) with more, but I suspect this might be as much down to folklore than experiment and measurement.

A more consistent room would likely use bass traps in all four corners and the first reflection absorption (side walls, floor and ceiling) and rear wall absorption/diffusion as a bare minimum. An even more consistent solution is measuring the room before and after treatment, but as audiophiles seem pathologically opposed to measurement, such a solution is unlikely.

i think it is fair to say that there is no common consensus. Such is audio. But I think it is also fair to say that if one is seeking an illusion of live music with their playback, ironically, a concert hall like envirement would be one of the worst choices. You would, among other things, have dueling reverbs. The reverb on the recording and the reverb of the room. That will lead to a mess. A concert hall is designed to impose it's sound on a live perfromance and this is widely considered a good thing. there is an entire art to concert hall acoustics. But playback is a different beast and for the most part we don't want a gross coloration of playback from the listening room if any coloration at all is desired.

That is the real question, is some room coloration a good thing. I don't think there is a universal answer to that since it will depend heavily on the speakers. Some are deliberately designed with certain assumed room colorations in mind. Certainly these speakers will likely suffer if those room colroations are removed.

As for anechoic chambers. An actual anechoic chamber is too expensive and too impractical for most audiophiles. There does seem to be an audio urban legend that they make for bad listening rooms. I have yet to hear that opinion come directly from anyone who has actually heard stereo playback in an anechoic chamber. IME every reduction in room coloration has lead to improvements. I am sure it is possible to do some harm if there is an imbalance in room treatments that would skew the frequency response of the room. Other than that, until I experience otherwise, I would assert that for my system every reduction in room coloration is a good thing to the point that all audible room colorations are eliminated. Should I ever reach the point where a reduction in room coloration adversly affects the subjective quality of the sound I will report it. I am moving to a new house some time between January and June next year and designing an ideal dedicated listening room is one of my goals. i should have lots to report when the time comes. as of now my plan is to design it so as to make it as free of colorations as possible and to make it so that I can easily adjust if that turns out not to be the perfect choice.

It depends on what you want to achieve with your listening room. If you're a classical listener listening to 2-channel stereo (stereo usually means 2 channel these days, but Snow's original meaning was "solid sound"), you might still want a live-end, dead-end room to provide some of the missing diffuse soundfield information.

If you're listening to multichannel that has the ambience added into the channels, then you might want something closer to anechoic, because you want to hear the ambience in the original, not whatever the room adds.

If you're listening to things like "Surround Sound" (2 to 5 channel systems, from the oldest "surround sound" to MPEG Surround, all of which have the same problems, only in different ways) you don't have any diffuse component when the signal is rendered, only direct sound from different directions. This is nothing like nature, but is, I suppose, ok for movies that can't be odne any other way.

In any case, you don't want: Specular reflections, huge bass modes, or any energy storage in the room that varies rapidly across frequency, either at low or high frequencies. (There is some argument about the "Schroeder Frequency" that might be wise to pay some attention to there, btw.) Such kinds of energy storage, even if "electronically compensated", will still have a very wrong time envelope compared to frequencies that are not stored in the room. Note: Especially at low frequencies, these kinds of storage problem are classic and well-known.

Bear in mind that a room that is not anechoic, but that has an ITU BS1116-like T60 is still perceptually anechoic, the direct sound from the speaker is going to mask the wall reflections.

Yes, the goal is for rooms to be free of audible ringing and echoes, have a neutral sound (ie: flat frequency response), with more or less uniform decay times versus frequency. But the size of the room is a factor for the ideal decay times. As you observed, a larger room can have longer decays and still sound good.



Yes, "larger than the room I can afford to own" is always the key.

--Ethan

Even for multichannel systems that properly capture the reflected sound in the original venue and provide it back to you via the playback system?

Put me on the record as questioning the notion that an anechoic chamber would be an awful place to listen to music.


...and for the record, I have been in a few anechoic chambers.

I've always been quite curious about what the experience of listening to music in an anechoic chamber would be like. My thinking is that it wouldn't be nearly as 'awful' as you believe. After all, a pair of headphones is something of a 'mini anechoic chamber', and though it's most certainly not a perfect comparison, some (most) headphones can definitely offer a very rewarding music listening experience.

...then show that little animation. It shows the direct wave and its first reflections in large recording room, 200 times stretched in time.

As far as you mount a loudspeaker on each of the mirror source positions and additionally loudspeakers for each of the different mirror source positions causing by different main source positions, the anechoic chamber would be proper solution. Yet, 1024.1 would cause new problems.

Besides, I would call into question the opinion the playback room should be as large as possible. I mean, should be adapted as well as possible. As example, the long detours for first reflections in large playback room cannot provide true spatial impression for a dialog recorded in a closed cabine of a car. As like as we need smooth response, we need adapted detours according the record content. Changing the playback room size up and down virtually is feasible today, though not in conventionally audio procedures.

A good listening room would be (1) Attached to my house, (2) Stocked with a large collection of music (3) Sound okay when I sit in my comfortable listening seat with my speakers four or five feet away (sit closer to the speakers and you hear less of the room)

In a good listening room, someone singing or playing an acoustic instrument live would sound good. Many home listening rooms are too small for accurately producing basslines, even if the bass musician is there playing his bass guitar live!

If someone sits where you want to place a speaker, and talks to you, while you sit where you'd like to place your listening chair, the quality of his or her voice is a good indicator if the proposed speaker location is a good one.

I have been inside anechoic chambers many times when working in product development at an auto manufacturer for almost three decades (anechoic to very low frequencies -- many others are not anechoic for bass frequencies). Music from car stereos and boom boxes (no real stereos inside, unfortunately) was very clear, but also "lifeless", and not that much fun -- an anechoic chamber would be great for the best possible movie dialog intelligibility when Marlon Brando mumbles his lines, except for one problem: When the music stops and there is silence, you can hear blood flowing in your body, which is spooky and annoying -- that's how quiet anechoic chambers are.

Uh, Richard, I have to disagree there. Quite aside from the room running in pressure (rather than propagation) mode, which ensures lots of bass, one can even introduce complex patterns into a small room, of course, not with 1 sub or two speakers...

My situation is an interesting one. I have recently had a new home built which includes a dedicated listening room. The dimensions of this room were relatively similar to my old room in my old house (which while dedicated and treated ... wasn’t built as a listening room) and my equipment list has been stable so the comparison between the two rooms is valid (relative to size and equipment).

As I am outfitting my new room myself, I have had the opportunity to run my equipment for testing at various points.

To keep this response short, when I was at the point where I had 4 inches of heavy grade mineral wool stuffed into the wall and ceiling cavities, my system sounded FANASTIC.. the best ever.

This might not be a true anechoic chamber but certainly we would have complete broadband absorption from around 150-200hz upwards.

Once the ceiling was lined and the room retested, it didn’t sound as good as before but this has since been restored with the application of a ceiling “cloud” of broadband absorbers.

I have also added in corner bass traps and 1st reflection treatments (remembering that by definition this was already there before due to the unlined but stuffed walls)

So the summary is… having what many people would call a “dead” room has made my system sound its best to my ears so I would say on reflection (pun intended), that I tend to side with Ethan on this.. all the cues are in the recording (or if not… that’s how the recording was made) so a completely dead room (as opposed to say dead end/live end) is at least a viable option. But whether you can, as I have been able to, validate this for yourself is another matter

I am now left wondering what to do with the parts of my walls that currently have no wall linings and only have the exposed cavity mineral wool… do I line these areas or just cover with an attractive cloth. (note. I am note asking for opinions here!!!)

This nearly describes what we did at AT&T. We put no drywall on the inner side of the room, left rigid fibreglass in our case between the joists, and covered thew alls with "Soundsoak".

It was not a revertabrant room.

jj

Me too, which is why I maintain they are an awful place to listen to music. I'm a two symphony in a single sitting kind of guy and I couldn't sit that long in a room that was slowly driving me crazy due to the lack of spatial cues.

I don't know if you can (or should) separate that from the performance of the loudspeakers in the room. If a room is notionally perfect for music replay, but creeps you out because of your reaction to the room, then it's a bad environment for listening. And I've spent long enough in anechoic chambers to know that doesn't go away... and it's not claustrophobia or being spooked by pointy things.

I'm not sure. I've never heard multichannel in an anechoic environment. I'd be making guesses.

How would someone "validate" your subjective preference? It's just a subjective preference (for deadness), no validation is required.


What was it's purpose?

I was wondering why you mentioned audiophiles, instead of professional audio engineers? Furthermore, from what I've heard, matching the speaker frequency response on the low end to the size of the lowest bass wave expressible in that particular size of room seems important; is this indeed correct? As well, isn't eliminating anything that can rattle or resonate and color the sound also important?

"Uh, Richard, I have to disagree there. Quite aside from the room running in pressure (rather than propagation) mode, which ensures lots of bass, one can even introduce complex patterns into a small room, of course, not with 1 sub or two speakers"
.
RG replies:
If you're lucky, the bassline in a typical home listening room (measured at a sweet spot listening position, using sine wave tones spaced 1 Hz. apart) will be in a +6dB/-12db frequency range, and even worse if you use one measurement rather than two measurements made 8" apart and averaged.

In plain English, that means the bassline will be rough. By typical room, I'm thinking of a 20' by 15' by 8' room, which I once read was the average-sized living room according to carpet installers. Bass in a near-square 13' by 12' by 8' bedroom would sound considerably more uneven. With small rooms, some fundamental bass tones will sound too loud and others too weak, due to standing waves, compared with really large rooms or auditoriums (where the uneven bass happens an octave or more lower, below the range of four-string bass guitars and modern kick drums).

There is rarely any pressurization in home listening rooms, as there is in cars with windows sealed where bass boost can reach 12db/octave, so "pressurization" is a moot point for home listening rooms which are rarely sealed well enough to generate any cabin gain.

If you did just cover it with cloth, I'd think the trick would be an acoustically transparent material as with speaker covers or grills. Another relatively inexpensive normal looking alternative I've seen used in listening rooms is regular heavy drapery, which is often used even over plain old regular walls.

Would that be pressure or velocity measurement, then?

Yes, this is a classical problem due to excess energy storage at bass frequencies, which means that in some places in the room, the bass energy is in the pressure, and in some other places, in the volume velocity domian.


I have to disagree with that, based on my own experience in frame dwellings. Maybe I buy good windows and doors, who knows? This even in a home with hot air heating and cooling.

In any case, your mention of multiple measurement points suggests that you are not capturing all four elements of the soundfield at one place. Are you simply using an omni (pressure) mike?

Using "Soundsoak" (Tm somebody) or "Acousticore" (TM somebody else) you can simply cover the walls with non-membrane backed soundsoak or acousticore, and you're home.

I previously wrote:
"There is rarely any pressurization in home listening rooms, as there is in cars with windows sealed where bass boost can reach 12db/octave, so "pressurization" is a moot point for home listening rooms which are rarely sealed well enough to generate any cabin gain."

You replied:
"I have to disagree with that, based on my own experience in frame dwellings. Maybe I buy good windows and doors, who knows? This even in a home with hot air heating and cooling."

My clarification:
My conclusion about cabin gain in home listening rooms is based on the measurements and word of Earl Geddes, who has written an excellent book on building a high quality home theater, and his own DIY home theater is an example. While I am able to measure cabin gain inside my closed automobile, trying to measure cabin gain under 30Hz. in a room at home is very difficult due to room noises, ranging from resonating walls to rattling dishes in the next room to resonating air inside heating ducts, along with increasing harmonic distortion from the bass drivers as the frequency declines. So I'll trust Earl Geddes measurements and conclusion over my own attempts to measure cabin gain at home.

Small rooms are best for loud uneven bass, if that's what you want. I've never read any credible source claiming that conventional small rooms are better than conventional large rooms for bass frequency response. If the small room had unconventional unusually flexible walls, and the large room had stiff concrete walls, it's possible the small room would have a smoother bassline at a typical seating position. But that would be a rare exception, not your typical plaster or plasterboard on 2" by 4" construction. Earl Geddes, by the way built a medium-sized home theater with three of the six surfaces using unusually flexible materials, to reduce the energy of the standing waves.

What do you propose measuring, other than sound pressure in the vicinity of the listener's ears using a sound meter, for the bass frequencies? And why would you want to measure anything else?

To the poster who wrote "... from what I've heard, matching the speaker frequency response on the low end to the size of the lowest bass wave expressible in that particular size of room seems important; is this indeed correct? "

RG replies:
Any room is large enough for bass down to 1Hz. ... A 20Hz. bass wavelength may be 110 feet long but you can still hear 20Hz. with good headphones even though the drivers play into a tiny "room" the size of your ear canals! And the easiest place to reproduce bass under 50Hz. is a inside a car with the windows closed. All this means is that when the the bass wavelength doesn't fit into a room, the bass driver pressurizes all the air inside the room (aka pressure pot effect) and you still hear the bass no matter how small the room is.

The primary problem with smaller rooms is uneven boomy bass. If you have several bass booms from standing waves in the octave from 20 to 40Hz., for example, it's possible an inexpensive speaker with little output under 40Hz. would sound BETTER than an expensive speaker that was flat to 20Hz.. But blame the small room's standing waves, not the expensive speaker's deep bass.

There are two fundamentally opinions in the matter. One thereof is Ethans view, all reflections include in the signal.
On the other hand many people are convinced the reflections of its undirected loudspeakers makes the best spatial impression.
In this context seem the experiments of Acoustic Research in the Carnegie Hall interesting. The signals of the artists was dry recorded. Each record was reproduced then from single loudspeaker, positioned exactly on the position of the (virtual) artist on the stage. The resulting reproduction was hardly distinguishable for the listeners regarding genuine event.
All we need for true spatial audio seem the correct starting points of the reflections. Provides the playback room matching pattern, the reproduction is perfect. As far as such pattern cannot establish in playback because of the too short detours of the reflected wave front, crush the reflections seems the lesser evil.

So it's clear, in general a large room IS better, but a small, very well damped room can also do a very good job.


Because I want to know the total energy stored in the soundfield. You?

Don't forget that you can always add synthetic reflections to a small room.

This would be terrific news if all my records were mono and recorded in an anechoic chamber and I had a world class concert hall for a listening room. But with stereo recordings recorded in reverberant envirements this just isn't how it works. You will not get any sort of spacial cues that corolate with the original acoustic event by bouncing the sound off the listening room with a stereo set up. Oh I don't know, you might get lucky with a few recordings but by and large it will not work. you will have battling reverbs from the listening room and the recording. On top of that the listening room reverb will be the reverb sourced from two speakers, not the original sound stage.

Yes, I know. Since some years i have a German Patent for calculate the correct starting points of such virtual sound sources. Klick that little animation.The model based approach combined recording room and playback room as common system.

Regards Helmut

Looks like you're halfway there!

I guess because the question is about what listeners prefer. An engineer or architect is going to design the room to the client's specifications.

Really? Would that not depend on the customer and the engineer?

For instance, what about a client who says "ok, you know your stuff, do it".

...I am sure.

Seriously, besides damping of the playback room directed radiation is the other possible possible solution for avoid misguiding cues caused by too early playback room reflections. I think the popularity of electrostats more caused by its directed radiation as by the superior quality.
But just like damping, the directed radiation alone a possibility for avoiding unwanted reflections. Yet for true spatial audio we need reproducing the reflections of the recording room, arriving from nearly correct directions.
Simulating the recording room reflections from delayed playback room reflections as in the Holophony approach possibly really the halfway.

No need to guess. It is what one (you) prefers.
A dead room with the resulting lower levels of spaciousness and clarity may not be for you at all.

cheers,

AJ

A good listening room should also contain a good equalizer (hardware or software).

Hmm, as my room gets deader the sense of spaciousness, or more exactly, the sense of transportation to another space improves.

This is my experience too. Always. Early reflections from nearby surfaces add a "small room" sound, and drown out the larger reverb and ambience that's embedded in many recordings.

--Ethan

yes but which one?

http://seanolive.blogspot.com/2009/11/subj...luation-of.html

Sufficient absorption in bass range for equally response a hard task. Electronic solutions like bass trap or equalising seems the only possible way.
But especially in the important mid frequency range there is a problem for electronic equalising. The superposition too early wall reflections cause deep notches. But those faults are caused in time domain. Resulting corrections in frequency domain always signal changes. Avoiding such reflection by absorption seems the better solution, if we have not the possibility for shift the wall away.
Besides, straighten the radiation posses the same effect as damping in that purpose, less too early reflections.

That's in line with the physics and the perceptual expectations?

Sound reproduction: loudspeakers and rooms
By Floyd E. Toole

Chapter 6 - Reflections, Images and the Precedence Effect:

I fail to see how this makes your point about dead rooms.

That a certain amount of reflections actually enhance clarity? Increase spaciousness? Both?
Or that, as I contend, we are dealing with subjective preferences, linked to polar and power characteristics of the sources?

cheers,

AJ

p.s. have you read Tooles or Geddes books?

Correct. Your post indicates nothing of the sort; only that early reflections do no harm.

My post clearly addresses which point you've failed to make so far, though you've not succeeded making this one, either.

I don't see how this is relevant to your attempt at justifying the quotation you've chosen.

Here's how room size works with speakers that have different amounts of bass extension.

Generally every revebrerent room has a frequency, below which the room starts interacting with bass in such a way that response increases with decreasing frequency. The smaller the room, the higher this frequency is. If your goal is the flattest possible response in the bass range, you want your speakers to start rolling off at the same frequency where the room starts providing this bass boost.

One familiar situation that sets this frequency relatively high is a car stereo. A car passenger compartment is usually a fairly small, generally well-upholstered room. If things like panel resonances and large flat reflective surfaces are avoided, it turns out to be a pretty nice room that is relatively easy to fill with bass. The inherently asymmetrical seating of the driver and passenger in the front seat is a problem. A small car can do amazing things in the bass range with a good 6.5" woofer.

An example of a mismatch of speaker and room is a small room with a speaker that has excellent bass extension. If you pick the right speaker will *less* bass extension, you might be able to get a merger between the bass rolloff of the speaker and the inhrent bass boost of the room, which starts at a relatively high frequency. A speaker that has too much bass extension will create a humped-up bass response. A speaker that has too little will create a hole in the response in the bass range and severely attenuated bass below it.

...there is a brutal distinction between first reflections in recording room and first reflections in playback room. Example:

In recording room first reflection detour is two meters longer as the way of the direct wave towards the listener. For 344 Hz the waves at the listener point in Phase, resulting level of superposition +4 dB.

At home detour is 0,5 meters. Because of the contrairy phase at listener point, at 344 Hz resulting level of superposition is - 20 dB .

The resulting comb filter pattern in recording room say yes, you are in the recording room.

The resulting comb filter pattern at home say no, you are in little, badly damped living room, assembled by two poor loudspeaker boxes.

A. K. wrote:
"Generally every revebrerent room has a frequency, below which the room starts interacting with bass in such a way that response increases with decreasing frequency. "

R. G. replies: Agree that cabin gain is real and measurable in a car with windows up. And that's why my car subwoofer, which was designed to roll off at 12dB/octave below 50Hz. has full output at 25Hz. in my car incuding the cabin gain, but is down about 12dB at 50Hz. when used in my large living room where there is no cabin gain.

According to the word and measurements of Earl Geddes, who you may know, few home listening rooms are sealed well enough to have cabin gain. Therefore, cabin gain would be a moot point for almost all typical home listening rooms, contradicting your post. But you'll have to argue this with Geddes -- I don't have the accurate measuring equipment, or a small room at home where nothing rattles, that would be needed for accurately measuring cabin gain.

In my experience with home subwoofers since 1980, if there is too much subwoofer output under 30Hz., the reason is an undamped standing wave under 30Hz., not excessive output from cabin gain. In a car, the cause of the same problem would be subwoofer bass roll-off that's not a mirror-image of the cabin gain bass ramp-up.

Well, maybe it's a question of whose house?

I've measured results that make it clear there's massive room gain at 50Hz in my old listening room (due to pressure, classic 12 dB slope). Certainly I had that problem in an old office at about 90Hz. Not in my current house, which has an open plan, and an enormous volume, so any gain would be well below any frequency that even Richard would care about