this paper describes the implementation of spectrally efficient ACELP based speech coding algorithm with a target bit rate of 7.2 per second (Kbps) suitable for speech communication over or wired line Communications. The 8 kbps ITU G.729  best speech coding algorithm has been modified so as to achieve lower bit rate and targeting low computational and search complexity, at the same time maintaining nearly the similar quality of speech reconstruction. The short-term spectral estimates are updated every 10ms (frame) and encoded as line spectrum frequencies (LSF). In order to reduce the bit rate and search complexity a pre-selection based sub-optimal, intraframe LSF vector quantization is proposed. The long-term protection (LTP) parameters are updated every 5ms (subframe) and implemented as modified open loop method (MOLP) with a pre-selection over a tri-valued speed signal, which considerably reduces the search complexity of the adaptive code book search. An algebraic structure and fixed code book based excite ation is proposed with reduced search complexity and combined optimisation of the LTP gain and fixed codebook gain for every subframe. The simulation results show that the performance of the proposed speech coding algorithm is nearly same as G.729 with lesser complexity and shorter processing delays.
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Cite this article:
Khan (2007). Reduced Complexity Low Delay, High Quality Spectrally Efficient Algebra Code Excited Linear Prediction (Acelp) Speech Coding Algorithm. Journal of Ravishankar University (Part-B: Science), 20(1), pp.1-12.