In the disclosed speech decoding device, activation of a postfilter process is halted during unvoiced sections. However, the updating process of the internal states of the postfilter continues even though the postfilter process is not activated during unvoiced sections. At changes between voiced and...http://www.google.com/patents/US5899967?utm_source=gb-gplus-sharePatent US5899967 - Speech decoding device to update the synthesis postfilter and prefilter during unvoiced speech or noise
