Automatic Speech Recognition on Mobile Devices and over Communication Networks

Part of the series Advances in Pattern Recognition pp 63-84

Speech Recognition Over IP Networks

  • Hong Kook KimAffiliated withDepartment of Information and Communications, Gwangju Institute of Science and Technology

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This chapter introduces the basic features of speech recognition over an IP-based network. First of all, we review typical lossy packet channel models and several speech coders used for voice over IP, where the performance of a network speech recognition (NSR) system can significantly degrade. Second, several techniques for maintaining the performance of NSR against packet loss are addressed. The techniques are classified into client-based techniques and server-based techniques; the former ones include rate control approaches, forward error correction, and interleaving, and the latter ones include packet loss concealment and ASR-decoder based concealment. The last part of this chapter is devoted to explaining a new framework of NSR over IP networks. In particular, a speech coder that is optimized for automatic speech recognition (ASR) is presented, where it provides speech quality comparable to the conventional standard speech coders used in the IP networks. In addition, we compare the performance of NSR using the ASR-optimized speech coder to that using a conventional speech coder.