Time Delay Estimation and Source Localization

A fundamental requirement of microphone arrays is the capability of instantaneously locating and continuously tracking a speech sound source. The problem is challenging in practice due to the fact that speech is a nonstationary random process with a wideband spectrum, and because of the simultaneous presence of noise, room reverberation, and other interfering speech sources. This Chapter presents an overview of the research and development on this technology in the last three decades. Focusing on a two-stage framework for speech source localization, we survey and analyze the state-of-the-art time delay estimation (TDE) time delay estimation (TDE) and source localization source localization algorithms. This chapter is organized into two sections. In Sect. 51.2, we will study the TDE problem and review a number of cutting-edge TDE algorithms, ranging from the generalized cross-correlation methods to blind multichannel-identification-based algorithms and the second-order statistics-based multichannel cross-correlation coefficient method to the higher-order statistics-based entropy-minimization approach. In Sect. 51.3, we will investigate the source localization problem from the perspective of estimation theory. The emphasis is on least-squares estimators with closed-form estimates. The spherical intersection, spherical interpolation, and linear-correction spherical interpolation algorithms will be presented.