LAMP Seminar
Language and Media Processing Laboratory
Conference Room 4406
A.V. Williams Building
University of Maryland

Tuesday Oct 26th, 1999
1:00 PM

Source Localization by Acoustic Measurements

Ramani Duraiswami
Institute for Advanced Computer Studies,
University of Maryland,
College Park, MD 20742


We will begin with a short introduction on the motivation of our work (combining acoustical and visual cues for perception), and an outline of ongoing work in our lab in this area. Next we will present a new source localization algorithm that we have developed in the context of a prototype audio-video teleconferencing system.

Source localization using the difference in time of arrival of a signal (TDOA) at an array of receivers is used in many fields including speaker location using acoustical arrays. Using three TDOA values from four non-collinear receivers one can, in principle, solve for the unknown source coordinates in terms of the receiver locations. However, the equations are non-linear, and in practice, signals are contaminated by noise. Practical systems often use multiple receivers for accuracy and robustness, and improved S/N, and solutions must be obtained via nonlinear minimization.

We have developed a new family of exact solutions, for source localization for the case of four receivers located in a plane. These solutions can be evaluated using a small number of arithmetic operations.

These solutions, however, are sensitive to noise in the delays measured, and multiple microphones (>4) can be used to improve the source location estimate. We have developed a new formulation for the source localization problem for multiple microphones. Our approach solves the source localization problem in stages, with appropriate optimization algorithms used for each stage, and incorporates the developed exact solutions. The present estimator is compared with ones from the literature, and found to be robust and accurate, and more efficient.

(work with Dmitry Zotkin and Larry S. Davis.)

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