Markus,
Sorry for slow response...
Btw. I played a bit more with sound/csound and etoys and came up with a new category "sound" where on can select the frequency and also "when" a sound should be played. I foresee csound to be pluggable there (currently it is kind of hard wired) so that one could choose between default Squeak Synth and csound Synth. I am aware of SoundSystem.
Ah, ok. We haven't gotten around including World Stethoscope code into our eToys image, but this is on our plan. Extending it with your idea (i.e., put a few more tiles) would be good.
It is already quite a lot of fun to animate several cars/ etc. and let them play some sounds with frequencies according to their y- position, possibly played with a delay according to their y-position.
Yes. WS happens to be able to do this, though not ready for playing different tone.
-- Yoshiki