While trying to make a pure-data synth, I have come to this problem, although I 've been using several filters.
Lets say I have an oscillator going το to a resonance / q filter.
Sometimes I get a "microphoning" (This is when sth goes wrong and you get a hissing sound with amplifying the wave's amplitude, just as you put the microphone in front of the speaker).
The solution to this problem is to change either the resonance or q (depending the filter) or changing (mostly dropping down) the cut-off frequency.
Why does this happen ?
What is the physics answer for this?