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Sound stage depth?

Wowarning

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I went to college for sound recording technology for a few years in the 90's. I admittedly didn't pursue a career behind the console, and my career in front of the console didn't pan out, but I have a fairly good understanding of what goes into making a recording (or what used to go into a recording anyway, lol.) I am a little confused at all the reviews of speakers that discuss the depth of the soundstage and how they can "hear the drums in the back" or "the guitar up front." When recording, there is only panning and placement of tracks across the soundstage left and right. There is no front and rear, or up and down. Especially in the situation of most modern recordings where instruments are close mic'ed and recorded at separate times I'm not sure what they're talking about. One scenario that I could potentially grasp the concept in would be something like an XY Stereo pattern mic'ing of a group of instruments where you could possibly get subtle timing cues that could create the illusion of depth, but I don't even know if that makes any sense. Can anyone shed light on how 'depth' is created or presented from a 2 channel recording being played back on 2 speakers? I'd love to hear Amir's take on this as well.
 

kthulhutu

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I went to college for sound recording technology for a few years in the 90's. I admittedly didn't pursue a career behind the console, and my career in front of the console didn't pan out, but I have a fairly good understanding of what goes into making a recording (or what used to go into a recording anyway, lol.) I am a little confused at all the reviews of speakers that discuss the depth of the soundstage and how they can "hear the drums in the back" or "the guitar up front." When recording, there is only panning and placement of tracks across the soundstage left and right. There is no front and rear, or up and down. Especially in the situation of most modern recordings where instruments are close mic'ed and recorded at separate times I'm not sure what they're talking about. One scenario that I could potentially grasp the concept in would be something like an XY Stereo pattern mic'ing of a group of instruments where you could possibly get subtle timing cues that could create the illusion of depth, but I don't even know if that makes any sense. Can anyone shed light on how 'depth' is created or presented from a 2 channel recording being played back on 2 speakers? I'd love to hear Amir's take on this as well.
As I understand it, proximity is usually simulated with amplitude differences and high shelving. Real depth would come from "purist" stereo miked or binaural recordings, not your typical mix.
 
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Wowarning

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Unless I somehow missed it, he didn't address soundstage depth at all in these videos. He discussed pinpointing instruments lt and rt across the soundstage and how the dispersion characteristics of the speakers affect that through room reflections. Can you specify a time in either of these videos that address what I'm talking about? If I missed it I'll look again.
 

fieldcar

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Ah, I though the video's covered a bit of Toole and Linkwitz's research. I know he provides small morsels of what's in these AES papers on psychoacoustics, but it's probably just scattered on a bunch of his videos.

From what I've gathered, there is significant importance to a good directivity index to create beneficial side reflections in a room that our ears and brain interpret as soundstaging due to the room's sound reflections. So, even if you had a completely DRY and simplistically panned recording of an instrument, a competently designed speaker with a good DI would sound realistic in a typical room.

Floyd Toole 2008
Sound Reproduction
“In-head localization seems like the logical opposite of an enveloping, external, and spacious auditory illusion. Perceptions of sounds originating inside the head, which routinely occur in headphone listening, can also occur in loudspeaker listening when the direct sound is not supported by the right amount and kind of reflected sound. The author and his colleagues have experienced the phenomenon many times when listening to stereo recordings in an anechoic chamber, usually with acoustically “dry” sounds hard panned to center or, less often, to the sides. It prompted an investigation (Toole, 1970), the conclusion of which was that there is a continuum of localization experience from external at a distance through to totally within the head. It is often noted with higher frequencies, and it can happen in a normal room with loudspeakers that have high directivity or in any situation where a strong direct sound is heard without appropriate reflections. Moulton (1995) noted that “speakers with narrow high-frequency dispersion . . . tend to project the phantom at or in front of the lateral speaker plane.” In an anechoic chamber, it can occur when listening to a single loudspeaker, especially on the frontal axis, in which case front-back reversals are also frequent occurrences. This phenomenon is so strong that it need not be a “blind” situation. Interestingly, a demonstration of four-loudspeaker Ambisonic recordings played in an anechoic chamber yielded an auditory impression that was almost totally within the head. This was a great disappointment to the gathered enthusiasts, all of whom anticipated an approximation of perfection. It suggested that, psychoacoustically, something fundamentally important was not being captured or communicated to the ears. An identical setup in a normally reflective room sounded far more realistic, even though the room reflections were a substantial corruption of the encoded sounds arriving at the ears.”

Here's a bit more reading.



 
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kongwee

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You can even create soundstage

You can make your instrument sound far away even they are close mic. It is all about the dry and wet signal ratio. Wet normally plugging in reverb. Some will use modulated delaying repetitive decaying of the dry signal to create the reverb.
Last part of the video, show you how to make the sound close on your face and send further back.
For some studio, they can just capture the room sound and control the mix later in the process which is something easier than using reverb.
 
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Chrispy

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I think we need a blind test with significant numbers of participants/samples to somehow map out where people think things are coming from with a variety of speakers/rooms with various recordings.....until then, meh.
 

DavidMcRoy

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This is what I was told, too.



Here is my opinion. It's worth what you paid for it. :)

As far as I can tell, the operative word here is "illusion". Myriad reflections contained in the recording are interpreted by our brain. They bear resemblances to sets of reflections that we hear in real life, in the world around us. The brain therefore compares these reflection patterns (on the recording) with 3-dimensional patterns that we've actually experienced in the world at large. If the comparison is a match, or reasonably close, then our brain provides the illusion of a 3-dimensional sound field, which includes the illusion of depth.

If the recording does not contain a set of reflections that the brain can recognize, there does exist an argument that reflections in the listening room can mimic the reflections of a 3-dimensional space in a recorded venue, providing the brain with a valid pattern that is not contained in the recording itself. I can't say anything about that; I don't know.

Jim
On top of these observations, I would expand to say that the human brain is constantly trying to "make sense of things," looking for recognizable patterns that it recognizes or "believes" it recognizes from prior events.

Also, our free will can interfere with attempts to listen in an objective way: we are "free" to sort of hear what we want to hear. And once we've "decided" that, for example, a centered mono source with no actual spatial cues associated with it based on time or phase actually sounds "distant" simply because it is somewhat reduced in level, has its highs rolled off a bit and has added reverb, then from then on we may "choose" to interpret that kind of treatment as an adequate illusion of depth.

For me personally, I can selectively "choose" to buy into that illusion or instead analyze what's is likely really going on and decide I 'm not in the mood to be fooled by it. Frame of mind is everything. (And if your speakers have a "BBC dip" at 2500Hz, things in the center are likely to be sound somewhat distant more often than not, exaggerating the illusion of depth.)
 

Kvalsvoll

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I went to college for sound recording technology for a few years in the 90's. I admittedly didn't pursue a career behind the console, and my career in front of the console didn't pan out, but I have a fairly good understanding of what goes into making a recording (or what used to go into a recording anyway, lol.) I am a little confused at all the reviews of speakers that discuss the depth of the soundstage and how they can "hear the drums in the back" or "the guitar up front." When recording, there is only panning and placement of tracks across the soundstage left and right. There is no front and rear, or up and down. Especially in the situation of most modern recordings where instruments are close mic'ed and recorded at separate times I'm not sure what they're talking about. One scenario that I could potentially grasp the concept in would be something like an XY Stereo pattern mic'ing of a group of instruments where you could possibly get subtle timing cues that could create the illusion of depth, but I don't even know if that makes any sense. Can anyone shed light on how 'depth' is created or presented from a 2 channel recording being played back on 2 speakers? I'd love to hear Amir's take on this as well.
Start by looking at the image of instrument placement on Jennifer Warnes - Bird On a Wire. Clearly, someone did indeed have an idea of instruments placed not only l-r, but also in the depth direction.

Exactly how this is rendered on a specific system, depends on speakers, placement, room acoustics. Some systems have a quite flat distribution with less separation in depth, others can have larger depth separation, and how each object is rendered can be very different. And of course, some systems only present a diffuse cloud of music.

Chesky Records has some excellent samples for depth, with drums and test signals, and the General Imaging Test has sound that travels around you, behind you, though this effect is difficult to reproduce in a convincing way. So soundstage on a 2-ch system extends from behind you, to indefinitely far away up front.
 

Inner Space

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I have never mixed anything in my life but my bet is relative level, delay and reverb.
And FR modification. Think of an oil painting - basically 2D, but the artist makes "distant" objects look distant by making them smaller (relative level) and not as focused as foreground objects (reverb) and duller, by moving the color palette toward the blue and gray (they call it "purpling") and we do it by removing HF, to mimic nature, where air resistance dulls treble faster than bass.

In theory the relative level makes for infinite depth control, but it never sounds that way, because of masking by foreground sounds. You can back stuff off, but it effectively dies altogether a few feet back.
 
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Wowarning

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You can even create soundstage

You can make your instrument sound far away even they are close mic. It is all about the dry and wet signal ratio. Wet normally plugging in reverb. Some will use modulated delaying repetitive decaying of the dry signal to create the reverb.
Last part of the video, show you how to make the sound close on your face and send further back.
For some studio, they can just capture the room sound and control the mix later in the process which is something easier than using reverb.
I get what these guys are saying and doing, but it isn't what I'm really trying to get at. To me, lowering the level of something and adding reverb to it can make it "sound" like it's farther away, but doesn't actually place it farther away in a 3 dimensional soundscape in my room. It just sounds quieter with reverb, lol. That might be a personal thing though, which I never really considered before. Possibly someone else's brain can hear the same thing and literally create a place in space farther away that they hear it coming from, whereas I'm just hearing levels and reverb.
 

Duke

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To me, lowering the level of something and adding reverb to it can make it "sound" like it's farther away, but doesn't actually place it farther away in a 3 dimensional soundscape in my room. It just sounds quieter with reverb, lol.

Once we bring speakers + room interaction into the equation, THOSE are the dominant factors in whether or not we hear a 3-dimensional soundscape. With some speaker/room combinations, there is a 3-dimensional soundscape which changes dramatically (and imo enjoyably) from one recording to the next.

You might think of it this way: In the playback room there is in effect a "competition" between the 3-D soundscape on the recording and the "small room signature" of the playback room. The ear/brain system tends to accept whichever package of spatial cues is presented the most effectively. If the "small room signature" cues inherent to the playback room dominate, then the best we can hope for is a really good "they are here" presentation. If the 3-D soundscape cues on the recording dominate, we can get a "you are there" presentation.

If you are not hearing 3-D soundscapes on your system, my guess is that the "small room signature" of your listening room is perceptually dominant.
 
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Wowarning

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Lots of great replies and interesting takes. I guess I'll settle in on it being an illusion, and one that I may be less susceptible to for whatever myriad reasons. It's also possible that I just haven't heard the right speakers in the right room that would make me say "holy cow, I can hear the guitar player standing in front of the drummer!" However, my brain tends to interpret level differences as something being "prominent vs buried," not "near vs far." Particular speakers having wider dispersion characteristics that can create early reflections in the listening room could certainly add to or take away from the illusion - I can get on board with that. I'm still a bit baffled by someone stating that a particular amplifier has much greater depth to the soundstage than another (which I'm sure everyone else here has also seen) as it really shouldn't have anything to do with it. Thanks everyone for sharing some great info!
 
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Wowarning

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For me personally, I can selectively "choose" to buy into that illusion or instead analyze what's is likely really going on and decide I 'm not in the mood to be fooled by it. Frame of mind is everything.
I think you completely nailed it here. I might perpetually be in the wrong frame of mind to allow myself to be tricked into thinking there's actually a band in my room. I've played in bands for so many years, that a pair of speakers is never going to replicate that in a convincing manner for myself.
 

pablolie

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The perception of "depth" is based on personal references/experience, let's say a large-ish classical venue. The depth often results in additional reverberation and similar effects, but it may well depend on venue, too.

And indeed, many recordings these days completely fake such effects, because it's all mostly artificially mixed together.
 
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