Linear predictive coding of speech using an analogue cochlear model

An analogue electronic model of a cochlea was developed some years ago by R. F. Lyon using a cascade of filters. Combined with an analogue gradient descent circuit, such an artificial cochlea can be used to extract the Linear Predictive Coding (LPC) of the speech signal in continuous time. We propose in this article an analogue VLSI circuit implementing a so-called 'Cochlear LPC' (CLPC). We discuss the expected advantages of the CLPC, such as an optimal time-frequency resolution and the continuous time processing. Furthermore we present some speech recognition results obtained using a computer model of the CLPC pre-processing combined with an HMM classifier. These results compare favourably with those obtained from a standard LPC/HMM system.