Subject: Re: Frequency response was Re: [linux-audio-user] Audiophile CD's
From: Ross Vandegrift (ross_AT_willow.seitz.com)
Date: Mon Jan 28 2002 - 07:16:30 EET
> BTW Just
> outa curiosity, I'm not wanting to start any major OT discussions but ..
> Is light actually wave, partical, both, niether, one or the other with
> properties of both????
Light is said to be a particle and a wave because if you look for it as a wave
it behaves like a wave. But if you look at it as a particle, it behaves like a
particle.
> I've always been really confused about the findings
> and never clear on the results or conclusionsions. It has often made me
> wonder (OK totally untrained mind with severe lack of discipline admitted to)
Hehehe, totally understandable. It's sooooo confusing!!!
> > Weisstein says in the CRC publishing of his website (which I purchased
> > before they sued him for the site...) under the entry for the Sampling
> > Theorem that to reproduce all of the Fourier frequencies for a waveform,
> > one must sample at a frequency f, where f >= 2B. Sampling at f = 2B is
> > called Nyquist Sampling. Sampling at f > 2B is called Oversampling, and
> > does not add artifacts or lose any information.
>
> Does sampling at f=2b loose any information?
Nope. Sampling at f=2b will capture the same information as f=3b or 4b or ...
The only difference is that for f=nb, for n > 2, you'll waste a lot of space
storing extra samples ::-).
> > Well, if a sound outside of my hearing range affects a sound inside my
> > hearing range, I don't need to study the sound that was too high - if I
> > could hear artifacts of the interaction, I can simply study the
> > interaction.
>
> I was under the impression the resonant harmonics, artifacts etc. can be the
> result of unheard as well as heard sonics interacting and that the playback
> (percieved sound) of subsequent recording would suffer if that data was not
> included with the recording or alter by adding it after the fact. similar to
> the phono preamp mentioned earlier for the "vinyl warmth" effect.
I'm not an acoustic enginner and I'm not a sampling theory expert. But this
idea just doesn't jive with the way waveforms work. If the following analysis
is wrong, someone _please_ correct it.
Let's say I have some waveform A that I can hear, and some waveform B that is
too high. Let's say that you are capable of identifying A (it's a simple 440Hz
sine wave). Now, assume that sounding A and B together produces an audibly
different sound. Since it is distinguishable from A, and B is inaudible, the
tone of A and B must be a different waveform (call it C; it's equal to A+B).
Since I can hear C, it must be below 22kHz. By the Nyquist Theorem I can sample
this waveform at 44.1kHz and capture it completely.
> >
> > > (you try playing a trumpet quietly (chuckle) but it don't sound much like
> > > a real trumpet).
> >
> > As a student of classical trumpet, I resent the implication present here!
> > ::-)
> >
> > Ross Vandegrift
> > ross_AT_willow.seitz.com
>
> Never in a million years would I ever wish to offend anyone purposedly.
> (by the smiley I'm assuming you understood my meaning)
Hahahaha - missed it completely! I had assumed you were joking about trumpet
players - we may be *capable* of playing softly, but none of us *like* to do so!
> And in reality, in our homes we do not wish to listen
> to a trumpet at reular volume but we want to hear it as if we were.
You're right - and I find this very interesting. Classical music people are
really the only exception, because most classical pieces have such huge dynamic
ranges. But for the most part, we all kinda look for our instruments to
compressed down to consistent volume from a full, healthy dynamic.
> But I'll risk it again Is classical trumpet related to 'regular' trumpet
> much the same as classical guitar is related to 'regular' guitar?
> Or do you mean classically trained?
I just meant classically trained, as opposed to trained on jazz/ska/avant
garde/etc.
> I've heard of Bach trumpets, which I assume were played with Bachs 'classical' music...
Bach is a popular brand of trumpets.
[snip]
> To capture realistically all the sound, sibilance, harmonics
> of an instrument that would never be heard in reality under real
> circumstances is the quest we're on?
>
> Or just to have something sound the way we want it to with the best quality
> we can muster with what we have to work with at the time.
100% agreed!
Ross Vandegrift
ross_AT_willow.seitz.com
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