Tobias Rodemann, Gökhan Ince, Frank Joublin, Christian Goerick, "Using Binaural and Spectral Cues for Azimuth and Elevation Localization", IEEE-RSJ International Conference on Intelligent Robot and Systems (IROS 2008), 2008.

It is a common assumption that with just two microphones only the azimuth angle of a sound source can be estimated and that a third, orthogonal microphone (or set of microphones) is necessary to estimate the elevation of the source. Recently, using specially designed ears and analyzing spectral cues several researchers managed to estimate sound source elevation with a binaural system. In this work, we show that with two bionic ears both azimuth and elevation angle can be determined using both binaural (e.g. IID and ITD) and spectral cues. This ability can also be used to disambiguate signals coming from the front or back. We present a detailed analysis of both azimuth and elevation localization performance for binaural and spectral cues in comparison. We demonstrate that with a small extension of a standard binaural system a basic elevation estimation capacity can be gained.