Sound generation recommendations?

[Charles Hixson]

I'm looking for a simple means of generatings sounds.  Basically what I 
want to do is play music from the information available in sheet music. 
I would like to send the commands to the player in relatively short 
bursts (the initial application is desired
to be a rising diatonic scale everytime the ball bounces off a paddle in 
a game of pong, based on tomspong.py (an SDL application).  I think that 
the beep function in the winsound module would work, but I want this to 
work on Linux and the Mac, and I don't even have a Windows box to test 
it on.

It would be nice if I could also specify the "instrument", for some 
definition of instrument.  But this would be useful only if I had access 
to a library of instruments.  Stereo might be a nice feature to add in 
later, but not yet unless it were really easy.  My feeling about this 
part right now is "KISS, or you'll be diverted from the parts that are 
more important.".

All the sound modules I've looked at seem to run off of sampled wave 
forms ... and this is nearly the opposite of what I want.