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Wireless Communications and Mobile Computing
Volume 2017, Article ID 9524943, 17 pages
Review Article

Acoustic Source Localization under Variable Speed of Sound Conditions

1Chair for Multimedia Communications and Signal Processing, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
2International Audio Laboratories, Fraunhofer-IIS, Erlangen, Germany

Correspondence should be addressed to Rudolf Rabenstein; ed.uaf@nietsnebar.flodur

Received 19 May 2017; Revised 14 July 2017; Accepted 1 August 2017; Published 17 October 2017

Academic Editor: Fabio Antonacci

Copyright © 2017 Rudolf Rabenstein and Paolo Annibale. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The rich literature on acoustic source localization mostly relies on the assumption of a constant value for the speed of sound. This hypothesis allows establishing simple relations between range differences and time differences and leads to effective estimation algorithms. However, it must be challenged for certain applications of wireless acoustic sensor networks in multizone buildings and outdoor environments. This article revisits the source localization problem for the more general case of an unknown value for the speed of sound. It reviews the physical foundations for the dependence of the speed of sound on the air temperature and presents the essential approaches to acoustic source localization. On this basis, several methods for source localization under uncertain or variable speed of sound conditions from the literature are discussed. Applications from different fields are shown. They comprise the localization of sources, sensors, and reflecting surfaces, time-difference-of-arrival disambiguation, and the direct determination of the speed of sound or the air temperature from acoustic measurements.