extracting beeps tone from audio?

Question

I have a beep sound file, I record it using a jack from the output of the soundcard to the input of the mic, the file is displayed with a lot of noise and the beeps having a known frequency (1-9) cannot be seen clearly, what filters or technique can I use to extract the beeps.
thank you .

Answer 1

9 seperate band pass filters would definatly work, but a better way is to autocorrolate the signal.
The random noise will cancel leaving you with the signal.

Answer 2

Use a band pass filter around the frequency of the beeps. You can do it digitally with an FFT, Fast Fourier Transforms resolve a continuous analog signal into discrete frequencies.