Incorporating image sources in the time-domain beamforming model for the localization of sound sources in reverberant rooms

In this study, we use a small hemispherical microphone array to locate impulsive or stationary sound sources in reverberant rooms. A modified version of the conventional time-domain beamforming model was used, which incorporates physical information from the early specular reflections of the sound source, as well as the geometric and absorption characteristics of the room. In other words, the propagation model takes into account the potential image sources up to a given image order. We show that the technique can be seen as a time-reversal process, the measured pressure field being simultaneously re-emitted from both the actual array position and its virtual image positions. We then present results applying this modified model to simulated data (generated using an image-source propagation model), as well as measurements in real rooms, using both impulsive and continuous broad-band noise. In all cases, the modified model shows an improvement in localization over conventional beamforming. The issue of appro...