Hi Sabai - Thanks for your comments, which are thoughtful and reasonable. It sounds like we have somewhat different views on the importance of the listening room, not only for creating the illusion that "you are there," but also for creating a sound that is "holographic." In my view...
In the listening room, the ambient cues of the room combine with the ambient cues of the recording. To the extent that the ambient cues of the listening room resemble the ambient cues of the recording, the listening room serves as a *simulacrum* of the recording space. I agree with both you and Learsfool that this is rare, both because typical recording spaces are so unlike the typical listening room and because the typical listening room is acoustically untreated. The problem, as I see it, is that the typical listening room is both...
1. Acoustically reactive, and
2. Acoustically distinct.
RE: 1. Acoustically reactive, or "live" rooms, provide an abundance of ambient cues. When those ambient cues fail to resemble the ambient cues of the recording, as they often do, the result is that the sound at the listening position during playback is acoustically contradictory, and therefore confusing. IMO.
RE: 2. Acoustically distinct rooms provide ambient cues that are highly recognizable. We all know what our own listening room sounds like. We have all been in public spaces with a distinct acoustical "signature." The more distinct the acoustical signature of the listening room, the more audible the differences between the listening room and the recording space will be. The result is that, during playback, acoustically distinct rooms are more likely to sound acoustically contradictory, and therefore confusing. Again, IMO.
Two solutions to these problems are to construct a listening room that is either
3. Acoustically non-reactive, or
4. Acoustically non-distinct.
RE: 3. Acoustically non-reactive, or "dead" rooms solve the problem of contradictory ambient cues by eliminating most of the ambient cues of the listening room. Hence most of the ambient cues heard during playback are the ambient cues of the recording. IMO, the flaw in this approach is that the ambient cues of the recording will be presented BIDIRECTIONALLY, or at best HEMISPHERICALLY, which tends to diminish the illusion that "you are there." Another common problem with dead rooms is that they can shrink the size of images and the size of the soundstage, both of which diminish realism. IMO.
RE: 4. Acoustically non-distinct, or "ambiguous" rooms solve the problem of contradictory ambient cues by having ambient cues that are less recognizable, and therefore less audible during playback. An acoustically ambiguous room sounds less like "that room" and more like "any room." Of course, no room can be perfectly ambiguous. But, IME, good listening rooms provide a range of ambiguity that reduces contradictory ambient cues during playback and therefore creates a more convincing illusion that "you are there."
To bring all this back to holographic sound. To me, holographic sound is about
a. realistic images, and
b. realistic soundstage (i.e. the spatial relations among images)
IME, realistic images can be achieved easily enough in acoustically dead rooms, with the qualification that acoustically dead rooms sometimes shrink images of instruments and performers to unrealistic sizes. IME, a realistic soundstage is more difficult to achieve in acoustically dead rooms, for the reasons I mentioned above.
Finally, I believe that efforts to increase the acoustical ambiguity of a listening room will make the soundstage more realistic on a wider range of recordings, and therefore acoustically ambiguous rooms are more likely to be holographic.
Just how to create an acoustically ambiguous room is not something about which I have any real expertise. I have some ideas, mostly gleaned from the characteristics common to the rooms I've experienced as ambiguous. The ambiguous rooms were...
-Reactive
-Large but not huge
-Few surfaces that create coherent reflections
-Lots of diffusion
-Medium reverberation time
-Mixture of surface materials
I dont know how to order that list, but the rooms Ive experienced as acoustically ambiguous had most or all of those characteristics, and probably others Im not thinking of.
IMO, IME, YMMV etc. etc.
Bryon
In the listening room, the ambient cues of the room combine with the ambient cues of the recording. To the extent that the ambient cues of the listening room resemble the ambient cues of the recording, the listening room serves as a *simulacrum* of the recording space. I agree with both you and Learsfool that this is rare, both because typical recording spaces are so unlike the typical listening room and because the typical listening room is acoustically untreated. The problem, as I see it, is that the typical listening room is both...
1. Acoustically reactive, and
2. Acoustically distinct.
RE: 1. Acoustically reactive, or "live" rooms, provide an abundance of ambient cues. When those ambient cues fail to resemble the ambient cues of the recording, as they often do, the result is that the sound at the listening position during playback is acoustically contradictory, and therefore confusing. IMO.
RE: 2. Acoustically distinct rooms provide ambient cues that are highly recognizable. We all know what our own listening room sounds like. We have all been in public spaces with a distinct acoustical "signature." The more distinct the acoustical signature of the listening room, the more audible the differences between the listening room and the recording space will be. The result is that, during playback, acoustically distinct rooms are more likely to sound acoustically contradictory, and therefore confusing. Again, IMO.
Two solutions to these problems are to construct a listening room that is either
3. Acoustically non-reactive, or
4. Acoustically non-distinct.
RE: 3. Acoustically non-reactive, or "dead" rooms solve the problem of contradictory ambient cues by eliminating most of the ambient cues of the listening room. Hence most of the ambient cues heard during playback are the ambient cues of the recording. IMO, the flaw in this approach is that the ambient cues of the recording will be presented BIDIRECTIONALLY, or at best HEMISPHERICALLY, which tends to diminish the illusion that "you are there." Another common problem with dead rooms is that they can shrink the size of images and the size of the soundstage, both of which diminish realism. IMO.
RE: 4. Acoustically non-distinct, or "ambiguous" rooms solve the problem of contradictory ambient cues by having ambient cues that are less recognizable, and therefore less audible during playback. An acoustically ambiguous room sounds less like "that room" and more like "any room." Of course, no room can be perfectly ambiguous. But, IME, good listening rooms provide a range of ambiguity that reduces contradictory ambient cues during playback and therefore creates a more convincing illusion that "you are there."
To bring all this back to holographic sound. To me, holographic sound is about
a. realistic images, and
b. realistic soundstage (i.e. the spatial relations among images)
IME, realistic images can be achieved easily enough in acoustically dead rooms, with the qualification that acoustically dead rooms sometimes shrink images of instruments and performers to unrealistic sizes. IME, a realistic soundstage is more difficult to achieve in acoustically dead rooms, for the reasons I mentioned above.
Finally, I believe that efforts to increase the acoustical ambiguity of a listening room will make the soundstage more realistic on a wider range of recordings, and therefore acoustically ambiguous rooms are more likely to be holographic.
Just how to create an acoustically ambiguous room is not something about which I have any real expertise. I have some ideas, mostly gleaned from the characteristics common to the rooms I've experienced as ambiguous. The ambiguous rooms were...
-Reactive
-Large but not huge
-Few surfaces that create coherent reflections
-Lots of diffusion
-Medium reverberation time
-Mixture of surface materials
I dont know how to order that list, but the rooms Ive experienced as acoustically ambiguous had most or all of those characteristics, and probably others Im not thinking of.
IMO, IME, YMMV etc. etc.
Bryon