Sampling rates don't need to be powers of two. Usually used sampling rates are e.g. 22050 Hz or 44100 Hz. Maximum signal frequency is half of the sampling rate,

Sampling rates don't need to be powers of two. Usually used sampling rates are e.g. 22050 Hz or 44100 Hz. Maximum signal frequency is half of the sampling rate, and sampling higher frequencies cause aliasing if they're not cut off first. So, 8096 Hz can sample up to to 4048 Hz without aliasing. If their cut-off filter is at 4000Hz, they're on the safe side by sampling a bit more, because the filter isn't perfect.