The writewav command writes sound data to a WAV file.
The writewav command takes two arguments; the name of a file and the sound data. The sound data can either be in the same format as that returned by the readwav command or (for a mono sound) a list of the digital data of the sound which will us the default parameters (16 bits, 44100 Hz).
writewav writes the sound to the named file.
The file la.wav will then contain a sound of frequency 440 Hz sampled 44100 times per second.