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A comment on Why do all these 20-somethings have closed captions turned on?. Parent comment

Re:Why do all these 20-somethings have closed captions turne... by galangalalgol on Sunday September 18, 2022 @09:44AM (#32887502)
Can you recommend a good explanation of the different types, how they are recorded encoded etc.? From a naive sonar perspective it seems like two mics one on each side of a head sized camera would do fine for encoding all the angle information. But then you would have to register and apply that knowledge to each boom mic input, and synthesize it for every sound effect that wasn't there at recording. Tl;dr Why isnt two channels enough to generate the correct output for N speakers spread around me?
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Re:Why do all these 20-somethings have closed captions turne... by lebuffon on Sunday September 18, 2022 @10:17AM (#32887756)
Left/right sound localization is partially a function of "shadow" created by the head. However more important to localization is the pinna, the outer ear. Sound enters the earhole directly AND reflects off the folds in the pinna. This causes complex comb filtering. (cancellation) Our brain learns how to correlate sound direction with these complex filterings. It's quite amazing.

Some audio workstations (Logic) have "binaural" processing to try and emulate this effect. It can never be perfect because everyone's ears are shaped a little different.

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Re:Why do all these 20-somethings have closed captions turne... by galangalalgol on Sunday September 18, 2022 @10:28AM (#32887857)
Right, that is how we do it. But isn't all the phase information present in two channels of audio to know how to map all the signals to an arbitrary number of angles? You'd need to know the spacing of the mics, but that could be a standard.

About the pinna, a fun way to demonstrate this is to have someone close their eyes, then you snap or jangle keys at various locations and have them point. Then tape their ears to their head and repeat. They will be way off in the vertical. We can do left right-ish (with coning error) without the outer ear. But up down is impossible.

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Re:Why do all these 20-somethings have closed captions turne... by lebuffon on Sunday September 18, 2022 @02:17PM (#32889928)
No. The phase differences for FULL localization are not in the incident sound. (There are phase and amplitude differences for left/right only)

3D phase changes occur and create comb filters at you ear and your ear is unique to you.

This is why Kunstkopf(dummy head) recordings were never as successful as anticipated.

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