A Framework for Speech Source Localization Using Sensor Arrays

of \A Framework for Speech Source Localization Using Sensor Arrays," by Michael Shapiro Brandstein, Ph.D., Brown University, May 1995 Electronically steerable arrays of microphones have a variety of uses in speech data acquisition systems. Applications include teleconferencing, speech recognition and speaker identi cation, 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. A fundamental requirement of sensor array systems is the ability to locate and track a speech source. An accurate x on the primary talker, as well as knowledge of any interfering talkers or coherent noise sources, is necessary to e ectively steer the array. Source location data may also be used for purposes other than beamforming; e.g. aiming a camera in a video-conferencing system. In addition to high accuracy, the location estimator must be capable of a high update rate as well as being computationally non-demanding in order to be useful for real-time tracking and beamforming applications. This thesis addresses the speci c 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 neareld environment, the evaluation of several error criteria available to the problem, and the detailing of source detection and estimate-error prediction methods. Several practical algorithms necessary for real-time implementation are then developed, speci cally the derivation and evaluation of an appropriate time-delay estimator and a novel closedform locator. Finally, results obtained from several real systems are presented to illustrate the e ectiveness of the proposed source localization techniques as well as to con rm the practicality of the theoretical models. A Framework for Speech Source Localization Using Sensor Arrays by Michael Shapiro Brandstein Sc.B., Brown University, 1988 S.M.E.E, Massachusetts Institute of Technology, 1990 Thesis Submitted in partial ful llment of the requirements for the Degree of Doctor of Philosophy in the Division of Engineering at Brown University