This MATLAB exercise illustrates the impact of mu law companding (compressing and expanding) and quantization of a speech signal. The program quantizes a speech file using a mu law quantizer with a bit rate of 'nbits' per sample, where 'nbits' is typically in the range of 2-10. The program plots the quantized signal and the error signal, along with an estimate of the signal and error power spectrum, and a histogram of the error signal values. The program also plays out the error signals in order to get a feeling for how much noise is introduced into the quantized signal at different bit rates. The file '5.5 Mu Law Quantization.pdf' provides a User's Guide for this exercise.