Propeller Head Plaza

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RE: Revisiting Heyser

Posted by josh358 on September 15, 2012 at 15:24:09:
"He proceeds this with a prophesy, 'Someday we will [have the technology] to record that [the dynamic diffraction pattern of an acoustic performance].'

"It has me wondering, 'Why not?' 34 years later!"

No reason, in principle, anyway. The Kirchhoff-Helmholtz integral says that you can do that with M-S microphones on a surface. A plane array allows you, in essence, to do it for the frontal sound.

In practice, I think we'll first see dry recordings of individual instruments or groups of instruments on separate channels and a position vector. This is just now being commercialized, e.g., by Dolby, and suitable standards already exist. Then this will be convolved with impulse response of the acoustic space and sent to a wave field synthesis array.

The impediments I think have included the large number of channels required -- a problem that is rapidly disappearing -- and cost of the WFS array. I think the WFS array will become economically practical soon enough as well. 1D arrays are already being commercialized. 2D arrays will I think require a heavily integrated approach to keep costs reasonable and so will need the involvement of the large consumer electronics manufacturers. Current off-the-shelf DAC's and amps would be I think too costly for a large 2D array, and that's assuming you had a signal to feed them -- you're going to need to do real-time convolution for all those channels, or have a recording of each channel.

I suspect we'll end up initially with a 2D WFS array in front, and a panned virtual sources approach for the surround.