Room correction, speaker correction anything above Schroeder a mistake?

[Kal Rubinson]

Is it possible that multichannel systems benefit even more from wideband correction than 2 channel systems? No idea whether it's indeed the case, just a hunch.

My hunch is that 2 channel systems would benefit even more from wideband correction than multichannel systems since they are more dependent on the distribution of reflections for the simulation of the stereo image. No idea whether it's indeed the case, just a hunch.

 

[Kal Rubinson]

I think the surround presentation is so captivating and effective that we forego other problems with fidelity.

Some may but if you pay attention you can appreciate proper EQ even so.

 

[Cosmik]

Another possible example of where acoustic effects measure badly but simply aren't heard.

While I try to minimize visible diffraction ripples in the frequency response for good measure, I have no evidence that even strong diffraction effects have significant audible consequences

The reason why they wouldn't be heard (according to my theory) is because they are 'deconvolutable' i.e. every frequency response variation is matched by a corresponding timing artefact so the human just hears through most of the effect.

 

[svart-hvitt]

Another possible example of where acoustic effects measure badly but simply aren't heard.

The reason why they wouldn't be heard (according to my theory) is because they are 'deconvolutable' i.e. every frequency response variation is matched by a corresponding timing artefact so the human just hears through most of the effect.

This should be measurable, testable, right?

Does frequency response compensation add problems (like timing artefacts)?

In other words: Does fixing 2D means messing up with 3D?

 

[Don Hills]

One thing worth pointing out about ERB filters. ...

Where's JJ when you need him?

 

[Blumlein 88]

The research shows the opposite. In that the more the channels, the less picky we become in how the individual speakers sound.

Here is research that Dr. Olive et. al. performed in effectiveness of room equalization as the number of channels is increased: https://secure.aes.org/forum/pubs/conventions/?elib=14622

Comparison of Loudspeaker-Room Equalization Preferences for Multichannel, Stereo, and Mono Reproductions: Are Listeners More Discriminating in Mono?

View attachment 9859


X axis is different Equalization methods. I have highlighted the surround ratings in yellow. We see there that there is very little difference there between No Eq and the other methods. Whereas in mono (blue), No Eq rated far lower than other methods.

I think the surround presentation is so captivating and effective that we forego other problems with fidelity.

Wouldn't these results tend to go against the idea our hearing can deconvolve the room effects from speakers?

 

[Cosmik]

This should be measurable, testable, right?

Does frequency response compensation add problems (like timing artefacts)?

In other words: Does fixing 2D means messing up with 3D?

I should think it could be tested - it's very similar to the comb filter experiment mentioned in Amir's paper earlier on..?

Another way of looking at it might be simultaneous equations. There's only one unique acoustic solution that would explain the result we hear, particularly as we move our ears around in 3D space.

If we really do hear through the acoustics, then for it to sound neutral to us the speaker would have to be neutral in terms of frequency response and phase/timing i.e. reproduce the signal verbatim. As Mr. Watkinson claims, when we fail to preserve the phase information using, say, a conventional crossover filter, we still recognise the results, but they have lost their absolute realism.

 

[RayDunzl]

Data Point:

In Stereo (two speakers) when you move away from the listening position, the impulse response changes from

to something like

 

[fas42]

The research shows the opposite. In that the more the channels, the less picky we become in how the individual speakers sound.

Here is research that Dr. Olive et. al. performed in effectiveness of room equalization as the number of channels is increased: https://secure.aes.org/forum/pubs/conventions/?elib=14622

Comparison of Loudspeaker-Room Equalization Preferences for Multichannel, Stereo, and Mono Reproductions: Are Listeners More Discriminating in Mono?

View attachment 9859


X axis is different Equalization methods. I have highlighted the surround ratings in yellow. We see there that there is very little difference there between No Eq and the other methods. Whereas in mono (blue), No Eq rated far lower than other methods.

I think the surround presentation is so captivating and effective that we forego other problems with fidelity.

Ah hah! This is rather nice confirmation of what I've found - the more 'intense' and enveloping the sound the less the FR matters. The easy solution, in current times, is to throw more equipment at the situation - more amplifiers, speakers, channels - whatever it takes to build the "presence" of the sound in the room.

I find it amusing that the word "discriminating" is used in the article's title - the question is, does the "intellectual" component of our minds switch on, to dominate the listening - or the intuitive? Like sampling a restaurant meal - "discriminating" would mean that we would assess that the food required 11.5% less salt, 23% more vegetable content, the plate it was served on should have been 8.5 % smaller - rather than, "Man, that was the best Indian food I've tasted in 20 years!!"

I certainly know from which angle I like the appreciation of "quality" to be derived from ...

 

[svart-hvitt]

I should think it could be tested - it's very similar to the comb filter experiment mentioned in Amir's paper earlier on..?

Another way of looking at it might be simultaneous equations. There's only one unique acoustic solution that would explain the result we hear, particularly as we move our ears around in 3D space.

If we really do hear through the acoustics, then for it to sound neutral to us the speaker would have to be neutral in terms of frequency response and phase/timing i.e. reproduce the signal verbatim. As Mr. Watkinson claims, when we fail to preserve the phase information using, say, a conventional crossover filter, we still recognise the results, but they have lost their absolute realism.

I would have liked to see that you and Mr. Watkinson are right. However, if you think about the stereo illusion ( see Ray’s post just above), I’m at a loss to see if the math survives tve wishful thinking. Isn’t stereo per se assuming that you’re listening at a very specific point?

 

[RayDunzl]

Isn’t stereo per se assuming that you’re listening at a very specific point?

It assumes (to some degree) that you are positioned equidistant from each speaker, not necessarily honed to a single point.

 

[fas42]

I should think it could be tested - it's very similar to the comb filter experiment mentioned in Amir's paper earlier on..?

Another way of looking at it might be simultaneous equations. There's only one unique acoustic solution that would explain the result we hear, particularly as we move our ears around in 3D space.

If we really do hear through the acoustics, then for it to sound neutral to us the speaker would have to be neutral in terms of frequency response and phase/timing i.e. reproduce the signal verbatim. As Mr. Watkinson claims, when we fail to preserve the phase information using, say, a conventional crossover filter, we still recognise the results, but they have lost their absolute realism.

What I've found is that I "hear through the acoustics" of the environment I'm in if the system overall is performing at a level such that the output of the speaker never supplies clues to its location - the "driver disappears" scenario. Virtually all systems are unable to reach this level - it normally is trivially easy to move closer to a particular speaker, and be able to "hear it working".

This is not frequency response, or phase/timing - it's the absence of low level distortion, noise artifacts; the ear/brain registers the presence of these, with ease - and the sense of realism is never engendered ... the illusion fails ...

 

[Cosmik]

I would have liked to see that you and Mr. Watkinson are right. However, if you think about the stereo illusion ( see Ray’s post just above), I’m at a loss to see if the math survives tve wishfum thinking. Isn’t stereo per se assuming that you’re listening at a very specific point?

As I surmised somewhere earlier, stereo may fool us because it cleverly hijacks the methods we use for locating sources of sound but using an arrangement of two sources that we could never encounter naturally. It is relying on a correlation between the two speakers. If there is a constant delay discrepancy between the two channels, this may not bother our hearing unduly because the correlation is still there. The stereo effect progressively (gracefully?) diminishes as you move from the ideal position but there is no falling apart of the music's tonality. Turning off one speaker doesn't cause an apparent shift in tonality.

Does the progressive separation of impulses from the two speakers as you move preclude the brain from still being able to do a form of deconvolution between the room and the speaker outputs?

 

[svart-hvitt]

What I've found is that I "hear through the acoustics" of the environment I'm in if the system overall is performing at a level such that the output of the speaker never supplies clues to its location - the "driver disappears" scenario. Virtually all systems are unable to reach this level - it normally is trivially easy to move closer to a particular speaker, and be able to "hear it working".

This is not frequency response, or phase/timing - it's the absence of low level distortion, noise artifacts; the ear/brain registers the presence of these, with ease - and the sense of realism is never engendered ... the illusion fails ...

Fas42, it seems to me like you're a natural member of group 1 (see post #35 for crude definition).

 

[svart-hvitt]

As I surmised somewhere earlier, stereo may fool us because it cleverly hijacks the methods we use for locating sources of sound but using an arrangement of two sources that we could never encounter naturally. It is relying on a correlation between the two speakers. If there is a constant delay discrepancy between the two channels, this may not bother our hearing unduly because the correlation is still there. The stereo effect progressively (gracefully?) diminishes as you move from the ideal position but there is no falling apart of the music's tonality. Turning off one speaker doesn't cause an apparent shift in tonality.

Does the progressive separation of impulses from the two speakers as you move preclude the brain from still being able to do a form of deconvolution between the room and the speaker outputs?

I think what I meant to say is this: Is your, and Mr. Watkinson's, thinking more relevant for mono source?

I can't make the math/logic on my own.

 

[fas42]

Fas42, it seems to me like you're a natural member of group 1 (see post #35 for crude definition).

Yes. I extend what Cosmik declares,

The stereo effect progressively (gracefully?) diminishes as you move from the ideal position but there is no falling apart of the music's tonality. Turning off one speaker doesn't cause an apparent shift in tonality.

to saying that the stereo effect is completely invariant, as you move from the ideal position - there is no "progressively diminishes", that registers as a subjective experience. This can only occur with a setup in extremely capable tune, which in turn is extremely rare - and perhaps this perception can only occur for a certain percentage of the populace.

 

[RayDunzl]

This can only occur with a setup in extremely capable tune, which in turn is extremely rare - and perhaps this perception can only occur for a certain percentage of the populace.

I estimate* that percentage to be 0.0000000131751507726837% (and dropping).


*fas42/WorldPopulation, i.e., 1/7,590,045,968

 

[svart-hvitt]

I estimate* that percentage to be 0.0000000131751507726837% (and dropping).


*fas42/WorldPopulation, i.e., 1/7,590,045,968

Sorry, couldn’t but think about this one:

 

[fas42]

I estimate* that percentage to be 0.0000000131751507726837% (and dropping).


*fas42/WorldPopulation, i.e., 1/7,590,045,968

Oowww, I can boost that at least a bit - in my travels I have crossed paths with of the order of 20 souls or so who "get it" - so, let's aim for a bit more than 0.000000262... %, eh?

 

[fas42]

So, for the rest - guess we will need to go the mega many amplifiers, speakers, channels; and ultra, ultra room treatment, and environment and DSP manipulation, route ... have fun!