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General Asylum General audio topics that don't fit into specific categories. |
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General Asylum General audio topics that don't fit into specific categories. |
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In Reply to: Re: No, it doesn't migrate down to audible frequencies posted by Mart on February 19, 2000 at 14:20:15:
I can't argue with what you hear... BUTThere aren't any "notes" above 10kHz in any instrument I know of, only overtones (harmonics). A above middle 'C' is 440. The highest A on a piano is 8x that, give a bit (a piano doesn't do it exactly right because of string stiffness). A flute can get 3 octaves above middle 'C' (262 Hz, give or take). That's a bit over 2K. A piccolo and a garklein go an octave above that, to a bit over 4K. That's about it for instrument sounds. Human voices don't stand a chance, and if you've ever been near a garklein going full tilt, well, you will appreciate what that 'C' amounts to. (ooooh, my head!)
Now, that's for fundamentals. Of course overtones go beyond that, or we'd not need any more bandwidth than a telephone.
I think you need to consider what it is you're not hearing (I'm not saying that it's nothing) but there just aren't "notes" up there.
Even things like cymbal rings, etc, don't have fundamentals up there, but of course they do have ring tones, which are NOT harmonic (which is why they sound like bells, of course).
I'm not sure what you mean by 'they analogy', but no, I don't. Any real filter does NOT have infinite cutoff. See the relationship expressed earlier that points out that t*f>=1, where t is time resolution and f is frequency resolution. That, alone, sets an absolute limit of how much time delay you must have vs. how close to fs/2 you can get, and that is a theoretical (and generally unachievable) limit.
In practice, the bandwidth is set to 20kHz. The filters start rolling off there and are down by 22.05kHz. So, there is no "analogy" or 'assumption' here, only some practical (and working) engineering.
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Follow Ups
- Please see above... You're making some odd assumptions - jj 14:35:16 02/19/00 (3)
- oops, typo ... analogy -> use an analog - Mart 14:52:53 02/19/00 (2)
- Ah, now at least that comment computes :-) - jj 15:59:21 02/19/00 (1)
- Re: Ah, now at least that comment computes :-) - Mart 18:29:42 02/19/00 (0)
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