Example code for signal processing using scipy.

1. analyse.py: reads a WAV file, computes the frequency spectrum using FFT, and plots both signal and frequency spectrum.
2. sound_plot.py: module containing helper function to format plots.
3. denoise.py: reads a WAV file, applies a Chebychev 2 highpass filter, and writes a new WAV file with the filtered signal.
4. create_signal.py: crates a WAV file based on a signal composed of a sum of sinusoidal functions.
5. Sounds: contains a few WAV files of bird calls to experiment with.