Abstract: A method of encoding an audio signal is disclosed. The method comprises partitioning the audio signal into a first time block and a second time block. Next, a first time block first energy value and a first time block second energy value are calculated. Next, a second time block first energy value and a second time block second energy value are calculated. Next, the technique determines if an attack has occurred in the second time block by comparing the second time block first energy value and the second time block second energy value and also comparing the Erst time block and the second time block Advantageously, the method identifies attach such that the decoder can reproduce the attacks with little audible distortion and also affords the advantage of using long windows for portions of the audio signal that do not contain attacks.

Abstract: A code excited linear predictive coder and decoder well suited to speech recording, transmission and reproduction, especially in voice messaging systems, provides backward adaptive gain control of stored codevectors to be applied to a synthesis filter prior to being compared with sequences of input speech signals. Simplified linear predictive parameter quantization using efficient table lookup procedures, efficient codevector storage and search all contribute in an illustrative embodiment to high quality coding and decoding with reduced computational complexity.