Patent ID: 8392182

Claim:
A method for encoding speech according to a source filter model, whereby speech is modelled to comprise a source signal filtered by a time varying filter, the method comprising: receiving, using a computing device, a speech signal; deriving, using the computing device, from the speech signal a frame of excitation quantization indices, each index being represented by a value and the frame comprising a plurality of blocks; and encoding, using the computing device, one or more parent blocks of values, the number of values being the length of each block, the method comprising for each parent block: (a) determining a first sum of values in the parent block; (b) splitting the parent block into smaller subblocks; (c) for at least one of the subblocks, determining a second sum of the values in the subblock, selecting a likelihood table from the plurality of likelihood tables based on said first sum of values in the parent block and encoding the second sum using the likelihood table; (d) designating each subblock a parent block; (e) carrying out steps (a), (b), (c) and (d) until at least one parent block reaches a predetermined condition.