Re: [microsound] High sampling rates/Bit depths

[Aaron Ximm <ghede@xxxxxxxx>]

> > There is no scientific research that shows humans to hear anything above
> > 20khz so unless Nyquist has been broken all the 96/192 talk is just
> > marketing. Manufacturers and dealers want to sell you new stuff.

I have heard differences at higher bitdepth that are quite striking,
sample rate differences less so but also discernible... but not in
rigorous blind testing!

I would love for someone with a gear chain to actually get higher sample
rates to the speakers to do a double-blind test for me of course.

Here are two reasons though a priori that higher sample rates are useful:

1) humans can definitely discern events, if not pitch, at smaller time
slices than implied by the 20 KHz canonical hearing cap; ie, we can
reliably use timing differences less than 5us to do things like
triangulate sound sources -- preserving that information is certainly
worth something;

2) Nyquist is good only for determining maximum frequency of square wave;
any wave shape differences are obliterated -- even a 5 Hz tone has very
few samples to differentiate a sine from a saw from a square at 44.1.
Personally I start losing ability to discern those things in high
frequencies but it'd be a useful test to render some simple waves at high
frequencies and then try recording them at different sample rates...

One slightly less a priori thought this is often used as an argument,
which I do somewhat buy into:

3) Any sampling errors (such as aliasing) in our methods near the Nyquist
frequency are pushed out of the [more] audible spectrum at higher sample
rates.

I'm looking forward to getting new kit when the reviews come back:  the as
yet unshipped Sound Devices 722 plus a pair of MKH-800 extended frequency
range multipattern mics from Sennheiser.  A field recording upgrade I've
long anticipated.

I'll be very, very curious to do some rigorous test recording at 16/44 vs
24/44 vs 16/88 vs 24/88 etc with mics and pres equal to the task... of
course, you rapidly hit the other half of the problem, which is getting a
playback system that can pass a signal let alone reproduce it well outside
of the de facto 20K limit...

 best,
  aaron

  ghede@xxxxxxxx
  http://www.quietamerican.org

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