Voice encoding for wireless communication based on LPC, RPE, and CELP

Abstract

Nowadays, voice encoders are one of the basic elements in the multimedia and telecommunications. This report explains properties of speech, how sound waves are generated and how they are classified and what is voice and unvoiced speech. A basic waveform encoding technique, Pulse Code Modulation (PCM) is introduced as the most common technique by changing an analogue signal to digital data. Three types of voice Encoder: Linear Predictive Coder (LPC), Regular Pulse - Excited (RPE) and Code-Excited Linear Predictive (CELP) are briefly discussed with Performance Comparison table between them is made to give differences summary. Finally, The Dynamic Rhyme Test (DRT) and Mean Opinion Score (MOS) methods are discussed as a voice quality tests to evaluate the performance of voice coders and checking the quality of the artificial speech.