At 1:03 AM +0000 4/7/10, Robin wrote:
>
>
>Dan Dugan wrote:
>
>> Mono recording piles everything together, and
>> some sounds obscure others. That is not how
>> humans hear--we hear in three dimensions.
>
>This is confusing two issues but it will take me a bit to explain
>why. We humans do indeed hear with ears that pick up sounds from all
>directions, but some directions are heard louder -- a lot more --
>than others. And of course this directionality is frequency
>dependent, with higher frequencies being much more directional (see
>HRTF).
I think Dan's is a good reduction. It takes two mics, two points in
space to create differences for the brain to go to work on.
>
>In the non-electro-acoustic world, sounds are (usually) emitted from
>point sources.
Hi Robin--
Emitted, yes, but sound "happens" in space. Every source portrays
space through reflections. When a sound seems to come from "one"
location, its the result of an expedient, perceptual construct in the
head.
> Thus a point source microphone suffices to capture the sound.
>Generally one will want this to be as directional as possible to
>(help) exclude other sounds. Those who wish to approximate the
>sensation of "being there" will want to capture the ambiance as well
>as the sound source. For this they might resort to more complicated
>recording techniques.
>
>Modelling one's microphone placement on human hearing makes sense in
>only one case: where you are planning on decoupling the listener's
>ears from the sound field during playback -- that is, for
>two-channel binaural recordings listened to on headphones. If
>instead you are planning on your sounds being heard over speakers,
>modelling human ears in the microphone placement introduces an extra
>HRTF to the signal. This makes no sense to me.
>
>Just as stereo speakers make no sense. No sound in the natural world
>is ever emitted from two places at once in that way. It is an
>approximation only, not an ideal. The fact that we have two ears and
>there are two speakers is a non sequitur.
>
>It is true that two recordings heard from one location might mask
>each other in cases where those same recordings heard from multiple
>locations will be distinct. But this is a matter for playback not
>recording. That's why my last soundscape recording was for an 8.1
>speaker system. I consider that a bare minimum to create an
>immersive sound field that can approximate the acoustic world. (16.4
>in a dome arrangement would be better.)
The more I work with surround sound the more I concentrate on getting
my stereo pairs to make compelling phantom imagery. I wish it was
simpler to achieve. Note that 4 channels > 8 stereo pairs and 8
channels > 16 stereo pairs.
The higher contrast imagery of "pin-point" approaches to surround
recording and playback are usually much more effective in loud
playback settings because phantom imagery is very delicate and
challenging to reproduce. Its challenging to document any sense of
depth without phantom imaging between the speakers.
>
>If I was fixated on verisimilitude I'd just use binaural and be done with =
it.
And the technique is great for producing verisimilitude with binaural
imagery. :-) Rob D.
>
>-- robin
>
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