Quote:
Originally Posted by J_P_A 
You may be right regarding the comb filtering. However, I think the phenomena that we are trying to replicate is much more complicated. The paper I linked to gives a good example of this. In a large concert hall, we hear a direct sound from the stage that is nearly perfectly correlated. The sound originates from the same spot and traveled the same distance to our ears on either side of our head. However, there is also sound reflecting from other surfaces in the concert hall, and some of those arrive at our ears a little later. The sounds arriving at the left ear have interacted with different stuff as well as traveling a different distance than the sounds arriving at the right ear. So both of these waves have a different "character" (or internal phase structure) than one another, and have a near 0 correlation. We've learned over the centuries to interpret this information and decide we are in a large reverberant space. Meaning if you were blindfolded and dropped in an concert hall, you would be able to identify that space as large and reverberant based on the sound signature alone.
You may be right regarding the comb filtering. However, I think the phenomena that we are trying to replicate is much more complicated. The paper I linked to gives a good example of this. In a large concert hall, we hear a direct sound from the stage that is nearly perfectly correlated. The sound originates from the same spot and traveled the same distance to our ears on either side of our head. However, there is also sound reflecting from other surfaces in the concert hall, and some of those arrive at our ears a little later. The sounds arriving at the left ear have interacted with different stuff as well as traveling a different distance than the sounds arriving at the right ear. So both of these waves have a different "character" (or internal phase structure) than one another, and have a near 0 correlation. We've learned over the centuries to interpret this information and decide we are in a large reverberant space. Meaning if you were blindfolded and dropped in an concert hall, you would be able to identify that space as large and reverberant based on the sound signature alone.
the ITD will dictate the perceived size of the acoustical space one is in. the resultant reverberant sound-field in a concert hall becomes the effective noise floor.
Quote:
Originally Posted by J_P_A
For our small listening rooms (relative to that concert hall) we don't have the benefit of of all that space to allow our sound to interact with stuff as well as be delayed, so we try to mimic that with our discrete sources. The original mixer will create a track for that single side surround by adding the sound effects that he/she likes, and by adding the appropriate amount of reverb to get the spaciousness that they want (I'm inferring that at this point). We want to essentially mix our own discrete channel, so we add a little delay to account for the path difference as well as add some reverb to further decorrelate our sounds. Again, we're trying to reproduce or predict that "character" or internal phase structure that would have occurred in the concert hall.
For our small listening rooms (relative to that concert hall) we don't have the benefit of of all that space to allow our sound to interact with stuff as well as be delayed, so we try to mimic that with our discrete sources. The original mixer will create a track for that single side surround by adding the sound effects that he/she likes, and by adding the appropriate amount of reverb to get the spaciousness that they want (I'm inferring that at this point). We want to essentially mix our own discrete channel, so we add a little delay to account for the path difference as well as add some reverb to further decorrelate our sounds. Again, we're trying to reproduce or predict that "character" or internal phase structure that would have occurred in the concert hall.
correct. a minimum volume is required to support a statistically random-incidence reverberant sound-field at a given wavelength and above.
in our small rooms, what little "reverberation" exists is typically at frequencies above our hearing range and below the ambient noise floor.
the "reverb" is merely an FX decay applied to the signal. that signal generated from the surround speaker is still emitted as a focused specular reflection within the bounded small room.
Quote:
Originally Posted by J_P_A
It may very well boil down to comb filtering, but that paper suggests that decorrelation reduces the perception of comb filtering. It may be semantics, however.
BTW, I'm using the term reverb, but that may not be the right thing to call this randomization of the phase structure. I'm fairly confident that's what we're trying to emulate, though.
It may very well boil down to comb filtering, but that paper suggests that decorrelation reduces the perception of comb filtering. It may be semantics, however.
BTW, I'm using the term reverb, but that may not be the right thing to call this randomization of the phase structure. I'm fairly confident that's what we're trying to emulate, though.
we use diffusers to break up the focused (sparse) specular reflections in the room that result in the polar lobing to create a dense array of reflections/lobing in order to get the "comb-filter" notches much more closely spaced together and dense.
Edited by localhost127 - 2/5/13 at 7:45am
I've got a feeling it's like watching someone ride a skate board, though. It looks easy, but there's a lot a skill involved. It still sounds like something that would be interesting to play with.
