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Re: [Phys-l] high frequency sounds



With a 44kHz sampling rate, one cycle of a 20 kHz sound wave will be represented by only 2 numbers. So above 15kHz, the digital version of the sound is not a very good 'analog'. I'm sure with today's faster electronics there can be more 'manipulation' of the signal--the oversampling rates range up to 16x--presumably checking and rechecking for accuracy even before corrections (based I believe on checksums) are generated -- waveform smoothing being one so that a missing bit or two doesn't create audible noise, even screeches. I don't know if anything is done with the very high frequency but poorly digitized signals. Anyway, the point is that there may be a lot there above YOUR hearing, but there is probably not a lot of information above the general range of hearing. I would actually suspect filters are used to cut out everything above some limit--18 kHz or so.

Rick



----- Original Message -----
>This may seem a bit odd, but I (supposedly) have some "high frequency"
sounds on a CD that are meant only for dogs to hear. Of course, I can't
hear anything when the disc is played! To be sure the disc is not blank,
is there any way that the sounds could somehow be reduced to "normal"
listening frequencies? Is there any software that could do this?