[sdiy] Harmonic bandwidth

[Ben Lincoln]

Achim sent me a comment off the list which I am going to paraphrase here 
since he's obviously quite smart, knows a lot about additive synthesis, 
and is apparently not going to post a similar comment on the list.

What he said was that I could hear a difference in the sounds when the 
base frequency was low enough (e.g. 100 Hz, like I've been using) 
because at that point the "differences in peak amplitude and/or slew 
rate" are getting into the area of fast envelope times (5-20ms). This is 
having the effect of amplitude modulation in the audible range. That's 
similar to what I was getting at with my original comment about 
constructive and destructive interference between the harmonics.

I also emailed a summary of the entire discussion to Barry Truax, one of 
the electroacoustic music professors at Simon Fraser University (where I 
studied about a decade ago). I'm not sure if I'll get a reply, but I'm 
hoping he'll at least be able to tell us if this has all been hashed out 
somewhere else already. I know he is pretty familiar with digital 
synthesis because he built his own hardware granular synthesizer back in 
the Atari ST days, so if it's an artifact instead of amplitude 
modulation, he will probably know about it.