Features for speaker localization in multichannel bilateral hearing aids

Modern hearing aids often contain multiple microphones to enable the use of spatial filtering techniques for signal enhancement. To steer the spatial filtering algorithm it is necessary to localize sources of interest, which can be intelligently achieved using computational auditory scene analysis (CASA). In this article, we describe a CASA system using a binaural auditory processing model that has been extended to six channels to allow reliable localization in both azimuth and elevation, thus also distinguishing between front and back. The features used to estimate the direction are one level difference and five inter-microphone time differences of arrival (TDOA). Initial experiments are presented that show the localization errors that can be expected with this set of features on a typical multichannel hearing aid in anechoic conditions with diffuse noise.