On Improving the Performance of Analys Multi-magnitude Algebraic Code-

In this paper, we propose a new coder based on the algebraic CELP(ACELP) coding technique. Our goal is to improve the quality of the obtained synthetic speech by a modification of the excitation signal of the classical coder. Such modification is accomplished by the variation of both the positions of the excitation impulses, and their amplitudes. The proposed algorithm consists of dividing the 10-ms speech frames into 2-ms sub-frames and assigning one impulse per sub-frame. These impulses are characterized by their optimized positions and amplitudes. Experiments show that our algorithm results in higher-quality speech with lower bitrate compared to the classical ACELP algorithm. It is shown that an improvement of 0.73 dB in the segmental SNR is achieved by the proposed coder over the conventional ACELP coder. Informal listening tests show that the synthetic speech signal obtained using our algorithm is perceptually closer to the original speech.