A practical methodology for speech source localization with microphone arrays

Electronically steerable arrays of microphones have a variety of uses in speech data acquisition systems. Applications include teleconferencing, speech recognition and speaker identification, sound capture in adverse environments, and biomedical devices for the hearing impaired. An array of microphones has a number of advantages over a single-microphone system. It may be electronically aimed to provide a high-quality signal from a desired source location while simultaneously attenuating interfering talkers and ambient noise, does not necessitate local placement of transducers or encumber the talker with a hand-held or head-mounted microphone, and does not require physical movement to alter its direction of reception. Additionally, it has capabilities that a single microphone does not; namely automatic detection, localization and tracking of active talkers in its receptive area. This paper addresses the specific application of source localization algorithms for estimating the position of speech sources in a real-room environment given limited computational resources. The theoretical foundations of a speech source localization system are presented. This includes the development of a source-sensor geometry for talkers and sensors in the near-field environment as well as the evaluation of several error criteria available to the problem. Several practical algorithms necessary for real-time implementation are developed, specifically the derivation and evaluation of an appropriate time-delay estimator and a novel closed form locator. Finally, results obtained from a real system are presented to illustrate the effectiveness of the proposed source localization techniques as well as to confirm the practicality of the theoretical models. (C) 1997 Academic Press Limited.