To heck with room acoustic treatments!!

[Tom Adams]

I read a comment the other day and it got me to doing one of those take a step back and do some clean slate thinking. And the question I pondered was, are we approaching this whole home theater thing wrong?

I mean, very few of us are able to build a theater room from scratch incoporating all of the acoustic treatments necessary. In most cases, we're forced to treat the room we have. Then, to throw a wrench in the works, we have to further tailor the room treatments to the speaker system we have. And in some cases, we might have to change it again due to a change in our speaker system. Lastly, there's the issue of speaker placement and how it not only interacts with the room, but determines spatially how the recorded sound "sounds" to us. Mind you, I'm restricitng this to surround sound home theater. You 2 channel only folks need to move along.

So here's where I'm going....what if a speaker system could be developed that could care less about the room? A system or device that would be akin to headphones, but larger in scale? Maybe it would be like a clear dome that you sat under that allowed you to view the movie through it or the movie would be displayed on its surface. The speaker drivers would be integral to this device and of a different type than what we know of today. And because each person had their own device, each device could be tailored for that person's unique hearing ability or lack thereof.

Hmmmmm.......what if????

Tom

[Colin]

sounds like corner horns to me-

or Bose auto EQ with 10.1 speakers 9 (so bass can be balanced through-out room)

I have always though that speakers should be made that actually sound better in a bookshelf....

[dbflash]

Tom,

I think they are called headphones.

Danny

[Colin]

yeah, light, wireless, surround sound headphones with built-in tube amps (10 microwatts)would be a great idea!

[Tom Adams]

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On 3/10/2005 10:37:58 AM dbflash wrote:

Tom,

I think they are called headphones.

Danny

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No, no, no Danny. C'mon dude....think out of the box. With headphones, the sound stays "stationary" regardless of which way you turn your head. That's not true. The direction sound eminates from should remain constant.

Colin - your response explains why you have no hair. You've done some serious head scratching in your day, huh?

Tom

[sfogg]

" So here's where I'm going....what if a speaker system could be developed that could care less about the room?"

That has actually been done a few different ways over the years.

One that caused a bit of a stir (then didn't really go anywhere) a few years ago was called the 'Hypersonic speaker' system or something like that. Carver (before they went under) licensed the technology but went out of buisness before they brought the system to market.

That system used a single driver per channel (with a specialized processor and amp) that was basically a very serious super tweeter that worked in the ultrasonic range. Because the wavelenth of the driver was much smaller then the driver it was extremely beamy and projected a very focused sound.

But of course humans can't hear ultrasonics. So this is in a nutshell how the speaker worked. The processor put out a carrier freqency up in the ultrasonic range. Then the music was modulated of that carrier freqency but again it was being reproduced all in the ultrasonic range. However when the two different waves interacted with each other they caused beat freqencies in the audible range... that was the music. I think it was fairly similiar to how radio works, just done with ultrasonics.

Because you had to be in the path of the ultrasonics to hear anything the room influenced the sound very very little. In fact it was claimed that it was so directional someone else in the room not in the path would just barely hear anything.

I don't think this was really a new idea as I think there was another speaker system built maybe in the '70s that did something like this.

There are also other ways attempts at making sound very directional too.

See:

http://www.holosonics.com/

for example. In that one the idea is literally to bounce the 'spotlight' off a wall near the people and that wall will be the apparent source of the sound.

Shawn

[D-MAN]

"I feel your pain".

1) I think that Khorns actually mate with a room "better" than free-standing speakers, although they, too, have their inherent problems.

2) I think that with a little knowledge MOST rooms can be made at least "tolerable" for audio with appropriate room treatments. But MAN, they are expensive and the worst the room, the more it costs - that's a major point of mass bummage!

3) Headphones and a floor (or chair) shaker COULD be the "poor-mans" approach, but it won't be a big crowd pleaser. Sort of like watching a movie on an airplane!

DM

[colterphoto1]

There was a system in like the 70's with a large semicircular band around the headrest of a recliner chair. Small speakers- like 5" auto variety were built in so the listener had a 'hands-off headphone-like' experience. I suppose some type of outrigger device could allow 5 channels of nearfield experience, but it would look ungainly.

I'm just waiting for the next generation whereby two small electrodes are implanted just behind the ears and sound transmitted directly to the auditory nerve. This would be similar to the cochlear implants in development today. Could happen!!

Michael

[Fish]

I may be missing something here but I thought the whole idea was a pile o gear and crank it up,you know,feel it.I don't think I could enjoy it as much if I only heard the music and could'nt see whats makin it happen.

[D-MAN]

Some more thoughts...

Unless we listen to music out-of-doors, or a REALLY big space, we are always going to be subjected to reflections and diffractions, no way out of that. That just comes from walls and floors and ceilings and floors. There is NO speaker that can exist in a room that you can listen to that the sound at your listening position is not subject to room-induced distortions of various types.

So the answer is to remove the room from the listening experience, and that means HEADPHONES. No room effects at all, as direct to the ear cannal as possible with no chance of escape or signal loss. But where's the bass? I want to feel it!

When you think about it, we are lucky to hear what we get from loudspeakers in our homes, which practically none are particularily acoustically designed. Most (especially mine) is pretty acoustically HORRIBLE.

I've heard some pretty crappy stuff actually sound great in the what seemed to be even worse circumstances. Why can't I get that to happen when it's my own gear in my own house which cost me lots of money?

It just ain't right.

DM

[minn_male42]

hey guys!

if you are using speakers with horn drivers, you should be one or two steps ahead of everyone else in this "room treatment" game...

the horns are much more directional than the dome tweeters that spread music in all directions

check out the following high end home theater setup from jbl synthesis.... about $120,000 just for the speakers and electronics (projector not included)

http://www.jblsynthesis.com/products/system_overview.aspx?prod=SYN-HERCULES&Language=ENG&Country=US&Region=USA

jbl uses horns to control dispersion and to make room treatments less extensive.... one of my customers in my last job was a jbl synthesis installer and told me that necessary room treatments with horns were about half as extensive as compared to speaker with all cone drivers...

[artto]

As has been already posted above, many attempts have been made to de-couple the loudspeaker from the room. This is irrational and about as likely as attempting to de-couple a singers voice or an instruments sound from the space it is in and have it still sound good to the human ear.

If one has an acoustically inferior space for the live musical performance, how does one achieve great sound from a superior performance? You dont. Something is lost. It is of no consequence that people, now and far into our past, have gone to great lengths and expense, to build fine concert halls/auditoriums which are capable of bringing out the best and most enjoyment from a live performance.

It seems to me that if you desire top performance from playback of these performances, one must also include the room as part of the equation. What do you think has the potential to produce a better result, a top notch playback system that is designed to decouple itself (as much as possible) from a typical room with inferior acoustics, or one that is designed to couple itself to the room, placed in a room that has superior acoustics? A system is only as strong as its weakest link. And for most audiophiles, the reality is, they generally ignore a major part of the system, which is the room itself, the final link. You cannot have the ultimate in sound production or reproduction without it.

[DrWho]

I've hesitated replying, but wanted to expand on artto's points...

The problem with decoupling the room (just like headphones) is the fact that we're dealing with "stereophony". It is impossible to record a live sonic event and then be able to play it back...even with perfect equipment, the very concept of using a speaker is fundamentaly flawed. I'm not sure I would be able to describe it without being able to use my hands to show what I'm talking about. I know there's literature out there that talks about this though. Anyways, the acoustics of your listening environment play a key role in accomplishing stereophony. There are a bunch of psychoacoustic variables involved but the most important is making sure the room always sounds the same...allow me to expand:

In a decoupled room (aka headphones or fancy speakers), there must be spatial cues added into the recording to help it sound more realistic. However, these spatial cues can only exist when the speakers are playing. Therefore any pause, any space in the sound will put the listener right back into his physical listening environment. Constantly switching back and forth between percieved environments totally distracts from the actual listening experience and is the fundamental problem with decoupling the room. Anyone else ever experience this?

[Klewless]

"There was a system in like the 70's with a large semicircular band around the headrest of a recliner chair."

I remember that chair. Now that I am a bit older, don't understand just why it was not successful.

Seems like a good idea. It goes without saying that an implementation must have top quality components and I see no reason that it could not accomodate 5 channels, with a bit of real creativity; maybe even with a sub thrown in for good measure. After all one has three dimensions to play with.

[sfogg]

" Constantly switching back and forth between percieved environments totally distracts from the actual listening experience and is the fundamental problem with decoupling the room."

Isn't that an arguement for having a room that doesn't add its own 'sound' to the recording?

Your recordings already have the acoustic space recorded in them, you just need a better method of pulling out those queues and getting them reproduced from the proper direction. IOW, a *good* ambiance extraction system using side and rear speakers.

When you have that you don't need or want the room to add its own 'signature' to the playback. And in fact it is an impedenment to great sound since the listener will be hearing two different acoustic spaces (the recordings and the rooms) which is a big tip off that what a person is hearing is fake.

Recordings are made in very different acoustic spaces... if we listen to the rooms acoustic signature it is the same for all recordings.

The exceptions to this are extremely dry recordings and those that aren't taking full advantage of the material that is in the recording.... which is most playback system... esp. two channel ones. For those systems you really do need to have the rooms 'signature' added to the playback to add some life to the music.

Shawn

[DrWho]

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On 3/12/2005 9:39:56 PM sfogg wrote:

Your recordings already have the acoustic space recorded in them, you just need a better method of pulling out those queues and getting them reproduced from the proper direction. IOW, a *good* ambiance extraction system using side and rear speakers.

When you have that you don't need or want the room to add its own 'signature' to the playback. And in fact it is an impedenment to great sound since the listener will be hearing two different acoustic spaces (the recordings and the rooms) which is a big tip off that what a person is hearing is fake.

Recordings are made in very different acoustic spaces... if we listen to the rooms acoustic signature it is the same for all recordings.

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I agree with most all that you're saying, but what I'm talking about is during the spaces in the music. When there are no sounds playing, you cannot have spatial cues present. During the spaces in the music (and when it stops), you will actually be hearing the spatial cues of your listening environment. Try sitting down with nothing playing and close your eyes. You can almost picture the room just by how it sounds...now go in the bathroom and do the same thing. These sounds that you hear with nothing playing will always be present. If your music is decoupled from the room, then you will be getting an entirely new set of spatial cues. In other words, it won't sound like it's coming from inside your room because the new spatial cues will clash with those of your room (instead of blending together). This is partly why listening on headphones is so obnoxious.

If on the other hand your speakers are allowed to interact with your room, then you will always have the spatial cues of your room present and therefore will not be switching back and forth. The spatial cues that are on the recording should mix with those of your room such that the recorded sounds will only be shifted in their percieved location. I suppose it could be argued that this deviates from having an "accurate" system, but I would consider it a worthy compromise.

Ironically, it is the trend in recording studios to virtually eliminate the room from the mic recording the sound. If this is the case AND our systems eliminate the room, then we'll have no spatial cues at all during playback...unless of course the mixer digitally adds those cues (ew).

Nevertheless, there are way too many variables involved to even consider finding an ideal scenario. What really needs to happen is a standardization of the recording studio and the playback room. I wonder how hard it'd be to plug away at the numbers and find a room (probably won't be rectangular) where the frequency response would be very flat and the reverberation sound natural. Over 90% of the mixing process involves making sure the mix will translate well. It really is a trivial matter to get recordings to sound good on the system you're mixing with.

[sfogg]

"When there are no sounds playing, you cannot have spatial cues present. During the spaces in the music (and when it stops), you will actually be hearing the spatial cues of your listening environment. Try sitting down with nothing playing and close your eyes. You can almost picture the room just by how it sounds.."

Not if you have a very quiet playback environment. Without extraneous noises in the environment you won't get reflections which can give an idea on the acoustic space.

"The spatial cues that are on the recording should mix with those of your room such that the recorded sounds will only be shifted in their percieved location."

It changes far more then just location. You get the sound of the 'size' of the hall in the recording overlayed on top of the 'sound' of the size of your room. Two contradicting queues... that of a large venue overlaid on top of a small venue. That makes it very obviously false.

Ever read about AR old live vs. recorded demos. They found that to fool the listener they had to make the recorded part extremely dry so that on playback the live and the recorded segments only had the acoustic space of the room it was being played back in. Otherwise the listeners could easily pick which was which.

"it is the trend in recording studios to virtually eliminate the room from the mic recording the sound. If this is the case AND our systems eliminate the room, then we'll have no spatial cues at all during playback...unless of course the mixer digitally adds those cues (ew)."

Which most studio music does. And if done with good exquipment... like the Lexicon 960L it can sound *very* good.

Shawn

[DrWho]

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On 3/13/2005 10:38:19 AM sfogg wrote:

Not if you have a very quiet playback environment. Without extraneous noises in the environment you won't get reflections which can give an idea on the acoustic space.

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But that's my point...an environment like you described without extraneous noices and reflections is still another environment from the one you hear in the recording. I think an anechoic chamber would be a perfect example of the kind of room to which you're refering...have you ever listened to recorded material in one? Even with surround sound providing some ambience it is the most unnatural listening experience ever. I had the opportunity to listen to a few recordings demonstrating different mic techniques...one of which was a stereo pair recording of some orchestral hall (very wet mix) and it still sounded very unnatural.

That said, I think we're after the same thing but are approaching it from two different angles. I would totally agree that a quiet environment is important as well as an environment without any resonances. After that, I think everything else is entirely an artform of trying to make your room fit the kind of music you listen to. As a sidenote, I think it's important to know what's going on in the studio because the engineer is naturally going to make it sound as good as possible to his own ear in his environment.

Btw, I have never used the lexicon 960L, but I have had the opportunity to use a few products from Lexicon's MPX lineup. I don't think they are totally capable of creating the illusion, though I've never tried one in an acoustically very dead environment either.

[sfogg]

"..an environment like you described without extraneous noices and reflections is still another environment from the one you hear in the recording."

Then there is nothing that can be done to fix that except have CDs that don't have dead silence between tracks, like how many live CDs are done.

You are either going to switch from having the acoustic space in the recording overlayed on top of the rooms sound, then just the rooms sound during the pause or in the other setup you will have the acoustic space in the recording, then nothing during the pause. I'll take the second option every time assuming it is used in a surround system.

If it isn't then I agree the room is going to need to add something to the recording on playback (and by definition something that is added that isn't in the recording is distortion) to make it sound more natural.

"I think an anechoic chamber would be a perfect example of the kind of room to which you're refering...have you ever listened to recorded material in one? Even with surround sound providing some ambience it is the most unnatural listening experience ever."

Have you heard it done using 7 channel surround sound? Or done outdoors?

Think of a binaural recording. A good binaural recording sounds *fantastic* when its playback has absolutely no influence from the room.

"Btw, I have never used the lexicon 960L"

If you ever get a chance you should spend some time with it. I got a demo of a little of what can be done with it at Lexicon and it was impressive.

I don't think the MPX line is in the same league as what the 960l can do with its 3D Perceptual Modeling. And the fact that it is a full multi-channel surround processor compared to the MPX line being two channel machines.

Shawn

[IB Slammin]

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On 3/10/2005 10:47:10 AM Tom Adams wrote:

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On 3/10/2005 10:37:58 AM dbflash wrote:

Tom,

I think they are called headphones.

Danny

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No, no, no Danny. C'mon dude....think out of the box.

With headphones, the sound stays "stationary" regardless of which way you turn your head. That's not true. The direction sound eminates from should remain constant.

Colin - your response explains why you have no hair. You've done some serious head scratching in your day, huh?

Tom

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HEY! Colin has a lot of hair!

Terry