[linux-audio-dev] Latency and feedback problems: soundcard with live microphone pass-thru, optimal solution ?

[James Courtier-Dutton]

Benno Senoner wrote:
> Hi all,
> I would like to route a microphone through a sound card and back to 
> powerful amplified speakers.
> 
> As we know in analog PA gear you have the microphone feedback problem 
> (usually it comes in form
> of high pitched whistle sounds).
> 

This problem is common as you know, and it has been solved a long time 
ago. The solution is to do a slight frequency shift to the audio.
Small frequency shifts are not noticeable to the listener, and that it 
what is used at all those loud pop concerts.

So, use ardour and do a simple real time sound capture, add a frequency 
shifter plugin, and then play it out all in real time.

Another application of feedback suppression is satellites where the 
forward uplink frequency is slightly different from the forward downlink 
frequency.

James