Removing Noise from sound Audio Recordings

[devKrishnan]

Is there any specific theory that states how we can remove noise from audio out put. I am a developer. I know no basics in terms physics about Audio, Noise . I record audio using an application in iPhone. I get lot of surrounding noise. I wanted to remove those noises. Is there any algorithm that will cancel the noises from the audio buffer I am getting out of my recording?

 

[cstoos]

Your best bet is to design a filter of some sort if it is truly noise (like 60Hz electronic interference). Study up on low/high/band pass filters.

If it is just background audio you are worried about then some sort of sound filter, like the styrofoam on the end of microphones will help cancel out unwanted sounds.

 

[devKrishnan]

Your best bet is to design a filter of some sort if it is truly noise (like 60Hz electronic interference). Study up on low/high/band pass filters.

If it is just background audio you are worried about then some sort of sound filter, like the styrofoam on the end of microphones will help cancel out unwanted sounds.

Thanks for the reply. I will look into those filters. What is this "styrofoam"? Is it a sort of physical filter to add to Microphone?

 

[timthereaper]

http://en.wikipedia.org/wiki/Styrofoam

 

[Mech_Engineer]

You should also look into the theory and design of condenser microphones, they do a good job of filtering out unwanted noise when recording audio:

http://www.mediacollege.com/audio/microphones/condenser.html

 

[devKrishnan]

http://en.wikipedia.org/wiki/Styrofoam

@timTheReaper: Thanks for the help. BUt I need a mathematical theory or algorithm that will cut noise.

 

[devKrishnan]

You should also look into the theory and design of condenser microphones, they do a good job of filtering out unwanted noise when recording audio:

http://www.mediacollege.com/audio/microphones/condenser.html

@Mech Engineer: Thanks for the suggestion. But I can not do any thing with the microphone of iPhone.

I need a mathematical theory or algorithm that will cut noise.

 

[Unrest]

I need a mathematical theory or algorithm that will cut noise.

There's not much you can do after it's recorded unless your noise and signal have some unique characteristics that distinguish them. If they're in different frequency ranges then there are plenty of filter algorithms available.

If the distinction between noise and signal depends on the context then there might be some sophisticated AI software, but don't bet on it. Or have a human operator edit the recording according to his knowledge of what you're trying to capture and what you don't want.