isn't there something like a main frequency in percussion and in general in all "objects"?
logically speaking, you would definitely have to say no.
if you just take a burst of random white noise, and run that through an envelope, it's going to sound something like a percussion hit. Really oldschool drum machines used not much more to create rudimentary drum sounds (snares, etc).
by definition, white noise is just a randomisation of all possible frequencies within the given bandwidth, so you really cannot say that there is any main frequency.
a lot of percussion contains such noise/randomisation elements, which certainly hinders the search for which 'tone' is most prominent.
then, you also run into the issue that the 'body' of percussion instruments will actually alter over time, thus creating a 'woop' upward moving tonality, or a 'doop' downward moving tonality. Old analogue drum modules usually have some sort of tone bend function to allow for this. If you try to do frequency analysis, then it's going to be hard, as the frequency does change over time.
something like your example of striking a glass is probably going to be your best bet to find a distinct tone, and in that case, you'll probably do well to ignore the first part of the sound, as the glass is first struck, and concentrate on the tail end of the sound where the glass resonates at its resonant frequency. You can use sigmund~. fiddle~, katja's new analysis tool she made (helmholtz~): http://puredata.hurleur.com/sujet-6776-helmholtz-guess
..or you could try to learn FFT and all that for yourself.
but it's a tricky one, i think....perhaps you should even start with just trying to analyze more traditionally 'tonal' sounds, and then see how you go from there? percussion would seem like just about the hardest thing you could possibly choose for a first project, i reckon.