Subject: Re: Frequency response was Re: [linux-audio-user] Audiophile CD's
From: Jason (hormonex_AT_yankthechain.com)
Date: Mon Jan 28 2002 - 10:16:04 EET
On Mon, 28 Jan 2002, Paul Winkler wrote:
> On Mon, Jan 28, 2002 at 12:59:10AM -0500, Jason wrote:
> > and C. Timbre however, is a function of waveshape not frequency; the
>
> But any periodic wave's shape can be *completely* described as the sum
> of sines of various frequencies and phases. Therefore timbre *is* a
> function of frequency.
True, but I'm not convinced that that necessarily means that everything we
hear is heard that way because our brains are constantly summing a bunch
of sine waves.
>
> > Therefore, higher sampling rates are desirable because they do improve the
> > accuracy of the repesentation of the shape of a waveform.
>
> ... by extending the frequency response.
>
> If you can hear the difference between a 22 kHz sine wave and a 22 kHz
> square wave, then you are hearing frequencies at 44 kHz or above.
> Either that, or you are hearing distortions in the playback system
> induced by ultrasonic content, which is quite possible.
And this is why the distinction matters, because I certainly can't hear
sine waves with a frequency much higher than 19.5 kHz, at least, not as of
the last time I had my ears checked.
However, I can tell the difference between a 16k sine wave and a 16k
square wave, and I can honestly say that the 16k square wave sounds like a
square wave, and not simply "different" from the sine wave- It's a pretty
easy test to execute, I suggest everyone
interested sampling frequencies conduct it at several different sampling
rates, it was a bit of a revelation for me- Which means
that either a.) you can hear much higher frequencies than 20kHz, and your
brain simply ignores them when they aren't associated with a lower
fundamental frequency (frankly, that seems a bit unlikely) or b.) The
brain doesn't process timbre by performing lightning quick FFT on the
input
from the audio nerves.
I guess it doesn't really matter, because both analyses lead you to the
same conclusion that 44.1 isn't really adequate. By the same token, it
makes it incredibly important that the higher frequencies are correctly
represented. In the last issue of Tape-Op there's an interview with Neve
that's pertinent to this discussion, he relates an anecdote about Geoff
Emerick noticing a slight brightness in three channels of the console at
AIR montserrat and
upon taking the thing apart, the discoved that the thing was 3dB down at
something ridiculous like 51k. For most people, I doubt it's something
they'd notice, and I doubt that Geoff Emerick can hear a 51k sine wave,
but still, it makes you think.
>
-- YankTheChain.com - You can pretend we're not here. That's what I do.,
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