Speech coding

About: Speech coding is a research topic. Over the lifetime, 14245 publications have been published within this topic receiving 271964 citations.

Distributed client-server speech recognition system

Abstract: A distributed speech recognition system includes at least one client station and a server station connected via a network, such as Internet. The client station includes means for receiving the speech input signal from a user. A speech controller directs at least part of the speech input signal to a local speech recognizer. The, preferably limited, speech recognizer is capable of recognizing at least part of the speech input, for instance a spoken command for starting full recognition. In dependence on the outcome of the recognition, the speech controller selectively directs a part of the speech input signal via the network to the server station. The server station includes means for receiving the speech equivalent signal from the network and a large/huge vocabulary speech recognizer for recognizing the received speech equivalent signal.

Vector sum excited linear prediction (VSELP) speech coding at 8 kbps

Abstract: The vector sum excited linear prediction speech coder is presented. It utilizes a codebook with a structure that allows for a very efficient search procedure. Other advantages of the VSELP codebook structure are discussed, and a detailed description of an 8-kb/s VSELP coder is given. This coder was selected by the Telecommunications Industry Association (TIA) as the standard for use in North American digital cellular telephone systems. The coder uses two VSELP excitation codebooks, a gain quantizer which is robust to channel errors, and a novel adaptive pre/postfilter arrangement. >

Speech Coding Algorithms: Foundation and Evolution of Standardized Coders

Abstract: From the Publisher: * Speech coding is a highly mature branch of signal processing deployed in products such as cellular phones, communication devices, and more recently, voice over internet protocol * This book collects many of the techniques used in speech coding and presents them in an accessible fashion * Emphasizes the foundation and evolution of standardized speech coders, covering standards from 1984 to the present * The theory behind the applications is thoroughly analyzed and proved

Adaptive postfiltering for quality enhancement of coded speech

Abstract: An adaptive postfiltering algorithm for enhancing the perceptual quality of coded speech is presented. The postfilter consists of a long-term postfilter section in cascade with a short-term postfilter section and includes spectral tilt compensation and automatic gain control. The long-term section emphasizes pitch harmonics and attenuates the spectral valleys between pitch harmonics. The short-term section, on the other hand, emphasizes speech formants and attenuates the spectral valleys between formants. Both filter sections have poles and zeros. Unlike earlier postfilters that often introduced a substantial amount of muffling to the output speech, our postfilter significantly reduces this effect by minimizing the spectral tilt in its frequency response. As a result, this postfilter achieves noticeable noise reduction while introducing only minimal distortion in speech. The complexity of the postfilter is quite low. Variations of this postfilter are now being used in several national and international speech coding standards. This paper presents for the first time a complete description of our original postfiltering algorithm and the underlying ideas that motivated its development. >