CELP and MELP speech coding techniques

Speech is one of the natural ways of communication amongst humans. Nowadays there is insatiable demand for speech communication as it carries more information like speaker identity, emotional state, prosodic nuance which adds naturalness in communication. With rapid growth and increased number of applications there exists a need for devising an approach for data compression techniques which reduces communication cost by using available bandwidth and storage space effectively. The speech coding techniques helps to achieve bit rate reduction by simultaneously maintaining original speech quality. In this paper, Hybrid speech coding technique i.e. Code Excited Linear Prediction (CELP) and Parametric coding technique i.e. Mixed Excitation Linear Prediction (MELP) are discussed and CELP technique is implemented using MATLAB. The parameters like mean square error (MSE), Mean Opinion Score (MOS), and Signal to Noise Ratio are calculated for CELP technique which shows that CELP technique is an improvement to a coder called Linear Predictive Coder (LPC). It is an efficient coding technique for the bit rate of 16-9.6 kbps. The MELP coder discussed here helps to remove the voicing error in two state excitation model of LPC. It is a low bit rate coder having a bit rate of 2.4 kbps and mainly used by military and federal standards.