if so multiply that bands which an adjustable value <1
but wouldn't that have weird effects when the signal you are attempting to remove the feedback from is the sound of you whistling?? Or is this method the one that many feedback supressors use? I thought it was something like mimicking the effect of constantly moving the mic around so that the frequencies at which the system is unstable actually move around, done via slow variable delays or something like that. Thats just a guess though.
You could use an adaptive line enhancer, if it was feasible to regularly calculate the inverse of a relatively large matrix and apply long FIR filters... tho on a laptop this is maybe a bit too hopeful.
The true way would be to keep the mic fixed in place and measure the response from loudspeakers to the mic, then calculate the optimal response to cancel the signal as it arrives at the microphone with a second source (maybe the right side of a stereo pair) and use an adaptive filter..... but as Thomas says it would require near zero latency and heck, a lot of cpu power!
Any ideas/improvements anybody?
Matt
-=-=-=-=-=-=-=-=-=-=-=- http://www.loopit.org -=-=-=-=-=-=-=-=-=-=-=- ----- Original Message ----- From: "sven" ml.sven@subscience.de To: robertgarvin@bellsouth.net; pd-list@iem.at Sent: Sunday, March 20, 2005 8:45 PM Subject: Re: [PD] feedback control
hi robert, feedback suppression should be quite easy to achive w/ the vasp external. fft the incoming signal. check if there are 1 or 2 bands which are much louder than their neighbours. if so multiply that bands which an adjustable value <1 and than take the ifft. feedback noise is a pure sine (until it's getting so loud that it' distorts) so they don't have overtones and cause a significant peak in at most 2 neighbouring bands.
sven.
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