RE: the beat goes on

>>I am not convinced that two pitches 100 and 101 sounded together
>>are percieved as 100.5 with a beat rate of 1. First how can this be
>>meaused.

>This is a standard result in psycho-acoustics. For instance,
>there's an extended description and a couple of figures describing it
>in Roederer's book (Physics and Psychophysics of Music).

This is an excellent book and I strongly recommend reading it -- you can
understand it even if you are not a physicist!