Soft Reconstruction of Speech in the Presence of Noise and Packet Loss
Farshad Lahouti, Amir Keyvan Khandani · IEEE Transactions on Audio Speech and Language Processing · 2006
Abstract—Exploiting the residual redundancy in a source coder output stream during the decoding process has been proven to be a bandwidth efficient way to combat the noisy channel degradations. In this paper, we consider soft reconstruction of speech spectrum, in GSM adaptive multirate and IS-641 vocoders, transmitted over a channel disturbed with noise and/or packet loss. Several schemes are presented which exploit different levels of intraframe and interframe residual redundancy for improved source decoding at the receiver. A packetization strategy is proposed which is matched to the presented error concealment units. For decoders that exploit the residual redundancy, extensive complexity has been a serious concern, especially as the quantizer bitrate increases. In this paper, a novel method is presented to construct reduced complexity algorithms. The proposed methodology is based on the classification of the signal domain and efficient approximation of the residual redundancy or the a priori transition probabilities. The presented schemes provide high quality error concealment solutions for code excited linear prediction (CELP) coders. Index Terms—Erasure channel, forward–backward recursion, global system for mobile communications–adaptive multirate (GSM–AMR), IS-641, joint source channel coding (JSC), linear predictive coding (LPC), line spectral frequency (LSF), Markov models, minimum mean squared error (MMSE) estimation, multiple description coding (MDS), packet loss concealment (PLC), residual redundancies, source decoding, speech coding, speech error concealment. I.