This file contains a mix of two audio clips: One of birds chirping, and the other of a flute. Your task is to remove the chirping birds, and recover (as well as you can) the original clip of the flute alone. (I would need to see an algorithm and/or code, as well as the final result.)
I will measure the error as follows: Convert your wave file to a vector, and normalise it to have length 1. (If your WAV file is stereo, both channels will be averaged to convert it to mono.) I will take the original wave file for the flute and convert it to a vector (again normalised to have length 1). The error will be half the distance between the above two normalised vectors. (The distance (as measured above) between the mixed clip and the original flute sample is about 0.2578. My code currently reduces this distance to 0.0446, at which point the birds are essentially inaudible, with very little “artifacting”. See if you can do better!)
I’d recommend using Matlab, Octave or SciPy/NumPy to do this. If you
choose to use Matlab/Octave, a few functions you’ll find helpful are wavread,
wavwrite, fft and ifft. If you use a different language, don’t reinvent the
wheel: find a library that read wave files and Fourier transforms functions.