ISSN : 1796-2048
Volume : 3    Issue : 3    Date : July 2008

Sound Source Localization with Front-Back Judgement by Two Microphones Asymmetrically
Mounted on a Sphere
Nobutaka Ono, Souichiro Fukamachi, and Shigeki Sagayama
Page(s): 1-9
Full Text:
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In this paper, we propose a novel system to localize a sound source in any planar direction using
only two microphones. In our system, the two microphones are asymmetrically placed on a sphere,
thus, 1) the diffraction by the sphere and the asymmetrical arrangement of the microphones give the
localization cue including the frontback judgment, and 2) unlike the dummy head system, no
previous measurements are necessary due to the analytical representation of the sphere diffraction.
To deal with reverberation or ambient noises, we consider the maximum likelihood estimation of
the direction of arrival with a diffuse noise model on a sphere. We present a real system that we
built through the investigation of the optimal microphone arrangement for speech. The experimental
results show that our system, which consists of two microphones mounted at ±46◦ angles on a
30mm-radius sphere, estimates a sound source direction including a front-back judgment with less
than 10% errors in real environment.

Index Terms
Sound source localization, sphere, front-back judgment, asymmetry, diffuse noise, ML estimation