Hello everyone,

I'm a student of the Fine Arts Academy in Poland and I want to make a project that involves auto gaining control.

The basic idea is that there is a microphone in the room -> microphone reads the volume of the people talking in the room -> speakers play sound (some constant buzzing or noise) a little bit louder than the people's tlaking

that creates a loop: if the buzzing gets louder - people start to talk louder - the buzzing gets even louder and so on. To stop the loop people should stop talking or they should stop fighting with the buzzing.

I can't find any help in my school. I've found PD and i thought it might be useful. I've watched some tutorials and I managed to do some simple real time voice distortions but I don't know how to make something that will work in the way I desicribed.

I know there might be a problem with the feedback.

Is my idea even possible to make? Is there someone who can help me?

regards

This is what I have right now. loop.wav is the sound that i'm loading from my hard drive.

http://www.pdpatchrepo.info/hurleur/mic-to-agc_loop.pd

It was wrong connected.
see inside the patch.

http://www.pdpatchrepo.info/hurleur/mic-to-agc-loop.pd

But it doesn't work, maybe I'm doing something wrong. I've opened the patch, loaded the wav. and it's not playing, even when I scream to the mic.

Do you know what's wrong?

DSP is on?

Yes, it's on. I've connected the volume slider and there was sound but it still didn't work in the way i wanted. I'ts not turni g up the volume when i speak louder

one more try

http://www.pdpatchrepo.info/hurleur/mic-to-agc-loop.pd

I've modified your patch a bit and it started to work! This is really close to the thing I wanted, I'm really glad! Check it

There's just this one thing, when the dbtorms slider is connected to the volume slider the sound of noise is at the same level as the volume of my voice in the mic. Is there a way to make the volume of the noise higher than the mic?

http://www.pdpatchrepo.info/hurleur/mic_agc_working.pd

If you play this loud enough, the mic will pick up the buzzing too, so it will just get louder by itself. If the buzzing is a periodic signal, you can use a comb filter to remove it from the incoming signal, before the AGC.

I know, I've already experienced this feedback. I was wondering if its possible to remove the noise from the incoming signal. It would be very helpful.

Ok, I found some information about comb filters but it's all too complicated for me, I just don't know what to do to eliminate the loud feedback. Is there an easier way? Or maybe someone can show me what to do.

Hello again,

I bought a bit more sensitive mic and the feedback is the real issue now. I've tried to make a highpass filter to cut off the low frequency signal that i was loading but it's not working, it's feedbacking anyway and it's also cutting the "speech" frequencies.

I want to cut off the wav. I'm loading and I want to pass only the "human voice" through the mic. I believe it should help with the feedback.

Can someone tell me what sound I should use to cut it off with the filters? Or maybe someone have different idea of how to deal with this problem?

I'm attaching the patch on wich I'm trying to cut off the feedback

http://www.pdpatchrepo.info/hurleur/mic_agc_working_nowy.pd

Hey kry_, I'm not sure how to go about doing off my head right now but in theory you could make use of inverting the polarity of the microphone to incur Phase cancellation. Right i'm entirely overthinking the possibilities of using it so I need to go let my brain simmer.

Start looking into it tho, it could be a viable concept. Working off the principle of noise cancelling headphones.

@RobTyler_10 said:

Hey kry_, I'm not sure how to go about doing off my head right now but in theory you could make use of inverting the polarity of the microphone to incur Phase cancellation. Right i'm entirely overthinking the possibilities of using it so I need to go let my brain simmer.

It depends on what noise is used. You can't simply cancel it because the noise will be affected by the room response, the distance between the microphone and speaker, etc. You can estimate an inverse filter (least mean squares filter) to compensate for this, but that's complicated. It's easy if it's something like a sine tone, because you can just remove it with a notch filter. But if it's white noise or something that varies rapidly over time, it's much more difficult.

So anyway if you don't want it to be overly complicated, use a noise signal that can be easily removed. Play a high frequency noise and detect only low frequencies, or something like that.

Oh, thank you so much for response.

So, I played the 5000Hz signal generated in Audacity and I connected the input signal to the lop~ and nothing really changed. No matter how high or low the number in the lop~ is, the noise is still there, its not cutting it off. Maybe I'm doing something wrong, look at my patch.

And what's with this sine tone and notch filter? How to do it? Maybe this is the solution?

once again, thanks for the response, I lost hope in this

http://www.pdpatchrepo.info/hurleur/mic_lop.pd

Is it too hard or just everyone don't give a shit about this?