Direction of Arrival Estimation Using the Rotating Equatorial Microphone

Journal article, 2024

Introduction: Direction of arrival (DOA) estimation of sound sources is an essential
task of sound field analysis which typically requires two or more microphones.
In this study, we present an algorithm that allows for DOA estimation using
the previously designed Rotating Equatorial Microphone prototype, which is a
single microphone that moves rapidly along a circular trajectory, introducing
DOA-dependent periodic distortions in the captured signal.

Methods: Our algorithm compensates for the induced spectral distortions caused
by the REM’s circular motion for multiple DOA candidates. Subsequently, the
best DOA candidate is identified using two distortion metrics. We verify our
approach through numerical simulations and practical experiments conducted
in a low-reverberant environment.

Results: The proposed approach localizes unknown single-frequency sources
with a mean absolute error of 23 degrees and unknown wideband sources with a
mean absolute error of 5.4 degrees in practice. Two sources are also localizable
provided they are sufficiently separated in space.

Conclusion: Whilst previous work only allowed for DOA estimation of a single
monochromatic sound source with a known frequency, our DOA estimation
algorithm enables localization of unknown and arbitrary sources with a single
moving microphone.