Hi David,
as Scott Fraser already pointed out, looking at the waveform alone might be
misleading here. Only slightly more than two samples per cycle can really look
terrible ;-)
You should instead look at the spectrogram, which inherently integrates the
individual samples over a longer period of time. You will then find out that
even very high-pitched calls that are close to the Nyquist frequency exhibit a
perfect shape.
Here is an example of a Blue Tit song sampled at 22.05 kHz, whose maximum
signal frequency is 8.7 kHz at the beginning of the first syllable:
Waveform: http://www.avisoft.com/sounds/blm2.wav
Spectrogram: http://www.avisoft.com/sounds/blm2.gif
Regards,
Raimund
> Record an ultrasonic
> cricket at 20 KHx, a shrew, a bat and the upper harmonics of a bird
> call and persuade me which is which with only two samples. :-)
>
> The Nyquist Theory is about aliasing, not resolution.
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