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Robotics Research

The ISL web site is maintained by Sean Andersson. Most recent update 03/08/01.

Auditory Localization

Directional sensing of sound enables the localization of its source in space. Many designed systems are comprised of free field sensor arrays and use time of arrival differences betweeen combinations of microphones to extract directional information. In nature, directional acoustic sensing evolved to rely on diffraction about the head with only two sensors- the ears.

Inspired by human sound localization we have developed and implemented an algorithm which compares measured interaural phase differences (IPD) and interaural level differences (ILD) to theoretical values to determine the direction of arrival. The algorithm and its performance are described in the following two papers.

  • A.A. Handzel and P.S. Krishnaprasad, "Biomimetic Sound-source Localization," IEEE Sensors Journal,2(6):607-616, 2002.

  • A.A. Handzel, S. Andersson, and P.S. Krishnaprasad, "A Biomimetic Apparatus for Sound-source Localization," 41st IEEE Conf. on Decision and Control, to appear.
Through the use of MDLe we have combined a sound-following atom which uses our algorithm with an obstacle avoidance atom to create a sound-following robot. Below we have several movies showing the robot in action. The current algorithm suffers from the "cone of confusion" common to binaural systems; that is the localization yields no information about the elevation of the sound source. In current work we are investigating dynamical ideas to break this symmetry. We have also used a broadband source; many auditory sources in nature, however, are narrow band (speech, for example). We are investigating the use of duplex theory in which the information coming from the IPD and ILD is weighted with respect to the frequency.