Marty Michener wrote:
a bunch of interesting stuff.
I have a few questions:
What mics and headphones did he find with such high frequency response?
It's not just the digital encoding that changes things, very little
equipment is made for going above the 20k limit by any significant
amount. Sennheiser, for instance seems to have only one mic that gets up
there at all, the MKH 800. And it stops way short of 80khz at 50khz. And
it's a pretty recent mic. You would also need custom mic pre's, special
analog recorders too. Even the analog recorders have cutfilters built
all through them in one form or another. And headphone design limits
their upper frequency too.
So, maybe what we are talking about is actually sound that's much lower
frequency, but precise measurement of the timing of the arrival of the
wavefront is how it's done. Phase shift calculations in other words.
Yes, digital can mess this up, but the flip side is that a cutfilter
working perfectly should not. Most real life filters produce some phase
shift, however, which is a timing change. I wonder if there has been any
examination on just what was getting through his system? What it's phase
shift was and so on.
And if it's phase shift that's used even we old geezers can do it. I can
certainly localize a sound precisely still.
Walt
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