Several methods for source localization from multimicrophone recordings are available. Source localization is also a topic in its own right for the analysis of acoustic scenes or for tracking of sound sources. The localization of sound sources provides information to enhance the desired source and to attenuate unwanted sources by beamforming techniques. For mirrored reflections also the reflector position may be of interest. A popular way to distinguish between desired and unwanted sources is by their direction or location. These unwanted sources may be competing sources, noise sources, or reflections thereof. IntroductionĪcoustic sensor networks attempt to record one or more desired sound sources in the presence of other unwanted sources. 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. Applications from different fields are shown. On this basis, several methods for source localization under uncertain or variable speed of sound conditions from the literature are discussed. 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. This article revisits the source localization problem for the more general case of an unknown value for the speed of sound. However, it must be challenged for certain applications of wireless acoustic sensor networks in multizone buildings and outdoor environments. This hypothesis allows establishing simple relations between range differences and time differences and leads to effective estimation algorithms. The rich literature on acoustic source localization mostly relies on the assumption of a constant value for the speed of sound.