how can the noise be removed from a recorded sound,using fft in MATLAB?

Question

I want to remove noises from a recorded sound and make the fft of it finding fundamental frequencies of that sound, but I don\'t know how to remove those noises. I\'m recording

Answer 1

Answer to your question is highly dependent on the characteristics of what you call "noise" - its spectral distribution, the noise being stationary or not, the source of the noise (does it originate in the environment or the recording chain?).

If the noise is stationary, i.e its statistical characteristics do not change over time, you can try recording a few seconds (10-15 is a good initial guess) of noise only, preform FFT, and then subtract the value of the noise in FFT bin n from your measurement FFT bin n.

You can read some background here: http://en.wikipedia.org/wiki/Noise_reduction