from wav to R

Dear all

I would like to perform frequency analysis of a sound (noise) 
recorded as a wav file (I would like to compare different sounds if 
they vary in frequency and how much). I know there exists some 
packages (Cool Edit) for doing frequency analysis of sounds but I 
wonder if anybody tried to do it in R.

I found a package sound. It enables to play with wav files, to 
append them and to make some filtrations. But if I wanted to 
invoke a spectrum() function it did not work with sound object.

Please can somebody give me a hint where to look or how to 
convert wav file to some kind of object analysable by R functions.