The µ-law method is a method used to increase the dynamic range of an audio signal before digital transmission. This method is described in the ITU recommendationG.711 and is used in PCM systems.
In µ-law compression, the dynamic range is increased by first sampling the signal at a higher bit rate and then compressing the data to a lower bit rate using a specific algorithm. The receiver of such a signal works in exactly the opposite way and restores the original higher bit rate.
Like the A-law method, the µ-law method also works with nonlinear characteristics and uses different quantization levels than the A-law method. Determining the bit rate is somewhat problematic in the µ-Law method, since the quantization samples are encoded logarithmically with 8 bits, whereas their dynamic range is encoded linearly with 13 bits. In the low level range, µ-Law has a steeper dynamic characteristic curve than the A-Law method.