A COMPARATIVE STUDY OF SPEECH CODING TECHNIQUES FOR ELECTRO LARYNX SPEECH PRODUCTION

Abstract

Speech coding is a method of earning a tight speech signals representation for efficient storage andefficient transmission over band-limited wired or wireless channels. This is usually achieved with acceptablerepresentation and the least number of bits without depletion in the perceptual quality. A number of speech codingmethods have already been developed and various speech coding algorithms for speech analysis and synthesis areused. This paper deals with the comparison of selected coding methods for speech signals produced by the ElectroLarynx (EL) device. The latter is a device used by cancer patients with their vocal laryngeal cords being removed. Theused methods are Residual-Excited Linear Prediction (RELP), Code Excited Linear Prediction (CELP), AlgebraicCode Excited Linear Predictive (ACELP), Phase Vocoders based on Wavelet Transform (PVWT), Channel Vocodersbased on Wavelet Transform (CVWT), and Phase vocoder based on Dual-Tree Rational-Dilation Complex WaveletTransform (PVDT-RADWT). The aim here is to select the best coding approach based on the quality of thereproduced speech. The signal used in the test is speech signal recorded either directly by normal persons or elseproduced by EL device. The performance of each method is evaluated using both objective and subjective listeningtests. The results indicate that PVWT and ACELP coders perform better than other methods having about 40 dBSNR and 3 PESQ score for EL speech and 75 dB with 3.5 PESQ score for normal speech, respectively.