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Old 6th February 2012, 23:37   #15
rockouthippie's Avatar
Join Date: Jun 2004
Location: Oregon
Posts: 11,002
I didn't look, but what is the sample rate? It might be why these recordings chirp. Anything above half the sample rate needs need to be filtered out. The absolute theoretical maximum frequency response of your CD player is 22050 hz (Nyquist frequency). In practice that's about 19khz.

If you try to record frequencies greater than the Nyquist frequency (1/2 sample rate) it will beat against the Nyquist frequency. i.e. record 30khz @ 40khz sample rate and you'll get a 10 khz tone.
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