a better fm demo

so i wasn't so satisfied with that one-liner i whipped up in class (i can't talk and code at the same time), so i quickly put together this video that will hopefully make things a little more clear. ah, FM... weren't the 80's delightful??

(pedantic side note: to make the math cleaner, i used phase modulation instead of frequency modulation, but the result is identical.)

if you'd like to play with these sounds, download supercollider and copy my example!



~fm = {(SinOsc.ar(440, SinOsc.ar(MouseX.kr(1, 2200, 'exponential'))*MouseY.kr(0, 100))*0.5)!2}.play;



some questions to think about (in case you enjoy thinking...):

1) sometimes the resulting spectrum is very harmonic and other times it's very complex. how might this relate to the frequency ratios between the carrier and the modulator? what kinds of ratios might produce a harmonic sound?

2) what effect might the index of modulation have on the spectrum?

3) at what approximate modulator frequency might our perception of the sound shift from a warbly vibrato to a complex spectral phenomenon?

4) jacob mentioned today that ringtones for cell phones often use FM to generate their sounds. why might this be the case?

5) who is john chowning and why is he so darned rich?