"They are here" vs. "You are there"

I am doubtful that on non-binaural recordings headphones can be said to give an accurate reproduction of ambient cues, or anything else, because of the fact that they bypass the pinnae, and inject the sound from the sides instead of from the front.

This is a good point, Al. I should have chosen an anechoic chamber rather than headphones to illustrate my view that omnidirectional ambient cues are more valuable than strictly accurate ambient cues for creating the illusion that “you are there.”

On a side note, how do you edit a post after it’s been posted? Can you give me a link to instructions here on A’gon?

Dgarretson – Glad that you joined in. I had never heard of the crossfeeding process you describe. I would love to hear it some day. Connecting it to this discussion, I would say that, like binaural recordings, it once again illustrates the importance of the DIRECTIONALITY of ambient cues for creating the illusion that “you are there.”

Cbw – Wow! A lot of great thoughts and insights.

Consider doing the playback in exactly the same space as the recording. You set up the speakers and the equipment to optimally reproduce the soundstage, and put the listener in the position of the microphone that recorded the performance. Thus, your listening space exactly reproduces the recording space. Is this the optimal space for creating the “you are there” experience? I don’t think so…

The real goal in this approach is not to PHYSICALLY replicate the recording space, but rather to approximate it in some important ACOUSTICAL parameters, including: relative balance of direct and indirect sound, relative balance of reflected/diffused/absorbed sound, time delay of first indirect sound, reverberation time, and so on. Optimizing these acoustical parameters of the listening space so that they have values that approximate those of the recording space is the kind of “resemblance” I have in mind. I should probably drop the word “resemblance” altogether from this discussion, because it does conjure up images of physical likeness. I should stick to words like “emulate,” to avoid the idea that this approach is about PHYSICAL resemblance. It’s not. It’s about ACOUSTICAL resemblance.

You are quite right to point out that acoustical resemblance during playback cannot be achieved simply by creating a facsimile of the recording space. Creating an acoustical resemblance between the listening space and the recording space takes into account things like the number of sound sources in the listening room (two, assuming you are listening in stereo) and the position of the listener relative to those sources and to room boundaries. It also takes into account a host of other variables, the manipulation of which, with any luck, results in a listening space that acoustically emulates the recording space, at the listening position. With that in mind...

The various kinds of room colorations you mention, what you are calling “source distortion,” “echo distortion,” and “temporal distortion,” are definitely things to be addressed. But it seems to me that these are precisely the kinds of things that an acoustically treated room DOES address. “Source distortion” is typically addressed by absorption or diffusion at the first order reflection points on the side walls and the ceiling. “Echo distortion” is typically addressed with diffusion behind the speakers. “Temporal distortion” is typically addressed by balancing the ratio of absorption to diffusion to achieve a specific reverberation time.

In light of this, I do not believe that the various kinds of distortion you mention are, in themselves, reason to believe that this approach is doomed to failure. IF this approach were tantamount to constructing a listening space that was a PHYSICAL replica of the recording space, then I would agree with you that it would be doomed. But the approach is to construct a listening space that, in important ACOUSTICAL respects, emulates the recording space, AS HEARD FROM THE LISTENING POSITION. It seems to me that that approach is not doomed to failure, though it is certainly bounded by constraints, both practical and theoretical.

So you have a range of recordings (from heavy cues to none), and a range of rooms (from live to dead), but it doesn’t seem possible to have an optimal room for both ends of the spectrum (which I think you’ve said)…

I agree that it is not possible to have an optimal room for all recordings. A person must choose on the basis of the recordings they tend to listen to, or the ones they are the most interested in optimizing, for whatever reason.

To sum up, I think to the extent that you succeed in making the ambience cues from the recording omnidirectional, they’ll be mis-timed, out of phase, and probably polarity flipped. And that is on top of all of the very strong room cues that you will necessarily generate to get the recorded cues to be omnidirectional. Or, to put it another way, I don’t think it is possible to get the recorded cues to be omnidirectional without seriously compromising the “you are there” effect.

This is an interesting argument. As I understand it, you are saying that the measures required to create omnidirectional ambient cues in the listening space would, in effect, destroy the accuracy of the ambient cues of the recording, as heard at the listening position. In a way, you are saying what Al said in point (3) of his post from 9/13 - what he described as a “tradeoff.” So my response to your argument is the same as my response to his observation: My view is that omnidirectional ambient cues are more valuable than strictly accurate ambient cues for creating the illusion that "you are there." Having said that, I guess I’m not as skeptical as you, Cbw, about the possibility of constructing a listening space whose acoustics allow for omnidirectional ambient cues that are REASONABLY ACCURATE to the recording. I wish I had the resources to build some rooms and put these theories to the test!

So, my theory:
1) Strong recorded cues + live room = a mess tending toward “they are here”
2) Strong recorded cues + dead room = “your are there” but bidirectional cues
3) Weak recorded cues + live room = “they are here” but if the room is sufficiently like the recording space, you approximate “you are there” for that space
4) Weak recorded cues + dead room = “they are here” (or in a studio)

Now this is a nice way of organizing things! But I don’t agree with it all. I think you are absolutely correct about scenarios (3) and (4). But, as I've indicated above, I don’t think category (1) would necessarily result in the “mess” you anticipate, provided that careful attention were paid to acoustical design. I am also doubtful that scenario (2) would result in the illusion that “you are there,” for the reason I have stated many times in this thread, namely that I don’t believe the bidirectional presentation of ambient cues can create the illusion that "you are there." In effect, scenario (2) is an approximation of an anechoic chamber, and I don’t believe you can create the illusion that “you are there” under those conditions.

Having said all this, I should reiterate something I mentioned earlier in this thread, but that may have been lost in the discussion by now: I don't believe that constructing a listening space that emulates a particular recording space is the BEST approach to building a listening room, for many of the reasons that have been pointed out, and some that have not. I do believe that it is a VALID approach, especially for audiophiles who tend to listen to one type of music. For folks who listen to a wide range of music with vastly different recording spaces, constructing a listening space that emulates a particular recording space is probably NOT the best approach. In the latter case, the best approach is probably a balance of:

(1) Emulation of some set of recording spaces.
(2) Creation of a listening space that provides a balance of attributes important for the hearing exactly what is on the recording.

To the extent that an audiophile chooses (1), he is favoring colorations over accuracy. To the extent that he chooses (2), he is favoring accuracy over colorations. (1) is the approach of some audiophiles who are primarily interested in creating a playback space that they themselves find interesting; (2) is the approach of recording studios, where accuracy is the Order of the Day.

The use of the word "coloration" above is not pejorative. Although I am an outspoken (read: notorious) advocate of the absence of colorations in equipment, I have a much more mixed view of colorations in the listening room. Although many listening room colorations are destructive (think: room modes, flutter echo, comb filtering, etc.), some room colorations, I believe, are beneficial. Among other things, they can enhance the illusion that "you are there."

A brief interruption to say a few words about the nature of this thread...

As Al pointed out several posts back, this thread is full of speculation. I myself have speculated at a furious rate. I just want to say that I do not regard speculation as great way to reach reliable conclusions. I regard carefully controlled TESTING as a great way to reach reliable conclusions. In that sense, I am an empiricist.

Unfortunately, I cannot currently afford to build a highly customized listening room, like some of the ones posted here on A’gon. In light of that, I am left to speculate on the basis of my experiences with (1) customized listening rooms for professional mixing; (2) customized listening rooms at audio dealers; and (3) my own quite humble listening room.

The purpose of this post is to explicitly acknowledge that I do not believe that speculation can ever be an adequate substitute for carefully controlled testing. Having said that, not all speculation is groundless. Speculation can be grounded on prior experiences, theoretical knowledge, and sound reasoning. I have made an effort to ground my speculations, though that may not always be apparent, which is my own fault. My thanks to other posters who, it seems to me, have made an effort to do likewise.

It would be nice if some folks with extensive experiences with customized listening rooms or expertise in acoustics would chime in, as it would elevate some of our speculations to the level of highly informed or even expert opinion.

Until that happens, let the speculation continue.

Hi Bryon - once again, you and Al and Cbw and Dgarretson have provided some excellent posts with much food for thought! Let the speculation continue, indeed! I have really enjoyed reading all of it, and you are certainly correct that although very few of us can design and build the rooms we might wish, there are many low cost ideas that can greatly improve any room. I envy all of the folks on this site who have a dedicated room, I don't even have that myself. Maybe in my next house!

Cbw – I have been giving more thought to your theory, and I have some fresh speculations…

You mention two parameters that determine whether a playback space creates the illusion that “you are there” or “they are here,” namely whether a recording has ambient cues or not, and whether the listening room is “live” or “dead.” To these, I think it’s useful to add a third parameter, namely, whether or not the listening space is acoustically similar to the recording space. With that in mind, I think there are…

FIVE SIGNIFICANT CATEGORIES:

(1) reactive room, ambient recording, acoustical similarity

(2) reactive room, ambient recording, acoustical dissimilarity

(3) reactive room, non-ambient recording

(4) unreactive room, ambient recording

(5) unreactive room, non-ambient recording

SOME DEFINITIONS TO GO WITH THEM:

-“reactive room” is a listening space with significant ambient cues. Hence a listening space that significantly interacts with the ambient cues of the recording during playback. A.k.a., a “live room.”

-“unreactive room” is a listening space with insignificant or no ambient cues. Hence a listening space that minimally interacts with the ambient cues of the recording during playback. A.k.a., a “dead room.”

-“ambient recording” is a recording that contains ambient cues of the recording space.

-“non-ambient recording” is a recording that does not contain ambient cues of the recording space.

-“acoustical similarity” refers to the acoustical similarity of the listening space to the recording space, as discussed in my second post from 9/14.

Each of the parameters that define the five categories is a continuum. A room is not either reactive or unreactive. Reactivity is a continuum, with maximally reactive rooms at one end and minimally reactive rooms at the other. Likewise for ambient cues on recordings. Likewise for the acoustical similarity of the listening space to the recording space. Since each parameter is a continuum, the five categories that they define are each idealizations, in the sense that actual members of each category will APPROXIMATE its idealized description.

Taking the five categories one at a time…

(1) reactive room, ambient recording, room similarity =

…YOU ARE THERE...

In my view, this maximizes the illusion that “you are there,” as I have suggested in earlier posts. I acknowledge, however, that this is not the most practical approach to building a listening space, since the greater the acoustical similarity the listening space has to the recording space, the LESS acoustical similarity it will have to different recording spaces, and the more your listening space will be “recording-specific.”

(2) reactive room, ambient recording, room dissimilarity =

…YOU ARE CONFUSED…

In my view, this would be the “mess” that Cbw was describing in his last post. To the extent that the ambient cues of the listening space are different from the ambient cues of the recording space, it could result in a confused, contradictory, or paradoxical set of ambient cues at the listening position. In other words, “you are confused.”

(3) reactive room, non-ambient recording =

…THEY ARE HERE…

In my view, the absence of ambient cues in the recording combined with a reactive listening space is what creates the illusion that “they are here.” This is perhaps the most straight forward of the five categories. And in some ways, it is the easiest type of illusion to create. Of course, if you don’t like the sound of your listening room, then you won’t like the way “they” sound when “they are here.”

(4) unreactive room, ambient recording =

…YOU ARE “ALMOST” THERE…

This is the trickiest of the five categories, I think. As I have argued in previous posts, I don’t think that you can fully create the illusion that “you are there” without omnidirectional ambient cues at the listening position. So, as a listening room becomes less and less reactive, I believe it will sound less and less like “you are there.”

Having said that, I should acknowledge that this comes close to creating the illusion that “you are there.” The bidirectional presentation of the ambient cues of the recording provides some significant information about the recording space, though as I have argued, it doesn’t present that information with the correct DIRECTIONALITY, which limits the illusion that “you are there.”

Of course, all this assumes that the playback is stereo. If playback were multichannel, then an ambient recording played back in an unreactive room could, in theory, create the illusion that “you are there." I say “in theory” because, as other posters have pointed out, most multichannel music mixes leave much to be desired, and hence typically fail to create the illusion that “you are there.” Nevertheless, the multichannel playback of ambient recordings in unreactive rooms to create the illusion that “you are there” is the prevailing methodology in movie sound, where it achieves some success, I think.

I should also acknowledge that there is a significant advantage to a SOMEWHAT UNREACTIVE listening room when playing back ambient recordings, namely, that it prevents your listening room from being “recording-specific.” But I don’t think that’s the ONLY way to prevent your listening room from being recording-specific (More on that in a future post).

(5) unreactive room, non-ambient recording =

…YOU ARE NOWHERE…

In my view, the absence of ambient cues in both the recording and the room creates an otherworldly “you are nowhere” effect, like you’re listening in outer space (yes, I know that’s impossible).

This may seem like a revision to what I said in my last post, when I agreed with Cbw that the category of “weak recorded cues + dead room” would result in the illusion that “they are here.” But I suspect that, when Cbw was referring to dead rooms, he was not referring to COMPLETELY dead rooms. Hence my earlier agreement with him that partially dead rooms (thus partially reactive) could create the illusion that “they are here.” I am now saying that, to the extent that a room is unreactive, non-ambient recordings will create the experience that “you are nowhere.”

Bryon, I agree that experimentation is really the only way to answer some of these questions and likely the only way to find an ideal listening environment for a person’s particular taste (aside from hiring someone who has the experience to design a room based on your expressed preferences -- though even that might take a few iterations or adjustments since it is unlikely that it will be right on the first pass (unless you’ve already heard exactly what you want and can point to it and say “I want that.”))

My point was mostly about the difficulty of getting the cues on the recording to be omnidirectional. If you achieve it, I think you also get a whole bunch of extra stuff from your room that you probably don’t want and would likely swamp the recorded cues. And even then, to the extent that the cues on the recording are omnidirectional, they’ll be mistimed and out of phase. I’m not sure it’s physically possible (outside of electronic intervention) to get the cues *on the recording* to be both omnidirectional and sound realistic.

The various kinds of room colorations you mention, what you are calling “source distortion,” “echo distortion,” and “temporal distortion,” are definitely things to be addressed. But it seems to me that these are precisely the kinds of things that an acoustically treated room DOES address. “Source distortion” is typically addressed by absorption or diffusion at the first order reflection points on the side walls and the ceiling. “Echo distortion” is typically addressed with diffusion behind the speakers. “Temporal distortion” is typically addressed by balancing the ratio of absorption to diffusion to achieve a specific reverberation time.

Right, I agree. But my point is again about the ambience cues in the recording. The primary signal in the music is generally going to dominate, and the cues are softer, lower SNR, and more diffuse. So, if you succeed in taming the distortions I mentioned for the primary, you also greatly diminish the omnidirectional nature of the cues -- probably completely out of existence. If you don’t succeed in taming the primary reflections, then they’re likely to overwhelm the reflected cues. But this is an argument from theory, and there may be some middle ground where it could work.

My view is that omnidirectional ambient cues are more valuable than strictly accurate ambient cues for creating the illusion that "you are there." Having said that, I guess I’m not as skeptical as you, Cbw, about the possibility of constructing a listening space whose acoustics allow for omnidirectional ambient cues that are REASONABLY ACCURATE to the recording.

If I understand you correctly, I think you are saying that one can, effectively, simulate ambience cues that approximate the cues on the recording, but are not sourced from the cues on the recording. If that’s the case, I agree (with the caveat that if the cues on the recording are strong and not well-matched to the room, you are likely to get a mess). To achieve this, you will be structuring your listening space to create a certain ambience. If that matches well with your music, you may have a very pleasing “live” sound. If it doesn’t, well, you’ll have to learn to live with it (or maybe have some movable absorption panels that can deaden the room effect when it’s not desirable).

I think, though, that purists will not like this approach. To the extent that you are creating ambience cues from the listening room, you are obscuring information on the recording. Learsfool, for example, might not like this approach for his listening, since he’s expressed a strong preference to hear precisely what is on the recording down to the differentiation of concert halls on fifty-year-old records. That probably wouldn't be possible in a room that was not very dead, or with a soundfield that was not very focused.