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# Separating two audio signal

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#### david90

I have audio signals A and C. C is an audio signal made up of A and B.

Is there a way to separate and isolate audio signal B from C? Assuming you don't have direct access to audio signal B and that you have to get it from C. Somehow.

It depends how C is made from A and B.
If C=A+B then B=C-A
If C=A*B then B=C/A
etc
First tell us how C is made from A and B and somebody will give you a circuit.

I have a mic in my car and C is made by the sound of my voice (B) and the sound coming out of my stereo (A). What i'm trying to do is somehow cancel out the music from my stereo from C so that the final output is just my voice or B. I can get A from my stereo output.

Is this possible??

David.

add an inverted A over C.
ideally, the sound waves from the mic and from the stereo should cancel eachother. but since the mic is not ideal, nor placed in an ideal position, you might hear some audio artefacts.

If you could get the frequency of all these signals and then you could filter it out then you can seperate the signal...
or
if you make to careers frequencies in which these 2 audio signals will be travelling then by filtering the career you can get the desired signals

Best Regards

I don't think you may talk about carrier frequency with two frequencies, both in the audio spectrum, since none is a carrier for the other.

You may try to modify the DNL (Dynamic Noise Reduction) circuit that was used to eliminate noise during playback of audio tapes ..
The prinicple will be similar: first, reverse phase of 'unwanted' signal and then add it to the composite signal .. something like this: A + B + (-B) => A
Here are details of the original DNL circuit:

Regards,
IanP

I see the problem this way. Microphone is somwhere in the car. On this place the left and the right speaker signals are different by amplitude. To subtract correct signal you need to add signals from left and right speaker with a ballance regulation. Between the speakers a potentiometer can be connected and sum is taken from the pot slide. Next you must add this summ signal to mic signal in propper phase and amplitude. Here is a circuit with gain and phase regulation using only one pot: