Free decisions for feedback compensation

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nick87720z
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Free decisions for feedback compensation

Post by nick87720z »

I thought very long about this problem after liscened some recordings from internet, then faced it visiting concert of one folk group.
Hardest search gave me this patent: http://www.google.com.tr/patents/US20070110254
I did not read it hard yet, but have own untested idea. And i'm not working with audio and even music professionally, so may be others could know about it.

Suppose, we have 3 - 5 players, each with own microphone, placed as close as possible to their instruments, sometimes some players may change instruments, e.g. flute to duduk, mandoline, etc. Feedback occurs when speakers output with hall reflections appears on all microphones at the scene.
One of wide-known way to compensate feedback, as i know, is to reduce most resonant frequencies by equalizer. However, it changes thembre, while sometimes may be not effective, as new frequencies may be revealed during performance, and operator must quickly react, adding new to equalizer.

My idea involves using convolver to fix input of each microphone:
1. Impulse responce is multichannel - one channel per microphone. If there are some electro-acoustic instruments, they are easiest to handle, as their sound doesn't go to other microphones directly, but they should not be ignored.
2. During work - sound from each microphone is processed by convolver.
3. Convolver output for each microphone is subtracted from pure microphone input.

And some questions:
- Better way to subtract: simple signal inversion doesn't seems to be reliable, as even constantly seating musicians may hold different instruments in different poses or slightly shift pose for single instruments, as they are not machines). One possible way might be using some kind of equalizer, taking impulse for subtraction. There might be even single effect, taking just an impulse instead of convolver's output.
- May be more known unclosed ways, which are more effective, than equlizer with manual setup?
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