The roles of inhibition and adaptation for spatial hearing in difficult listening conditions

Acoustical Society of America (2017)
doi: 10.1121/1.4987838
Acoustical Society of America meeting 2017
Abstract. The computation of binaural cues such as the Interaural Time Difference (ITD) and Interaural Level Difference (ILD) by the auditory system is known to play an important role in spatial hearing. It is not yet understood how such computations are performed in realistic acoustic environments where noise and reverberations are present. It has been hypothesized that robust sound localization is achieved through the extraction of the ITD information in the rising part of amplitude modulated (AM) sounds. Dietz et al. (2013) tested this hypothesis using psychoacoustics and MEG experiments. They presented AM sounds with ITDs varying during the course of one AM cycle. Their results showed that participants preferentially extracted the ITD information in the rising portion of the AM cycle. We designed a computational model of the auditory pathway to investigate the neural mechanisms involved in this process. Two mechanisms were tested. The first one corresponds to the adaptation in the auditory nerve fibers. The second mechanism occurs after coincidence detection and involves a winner-take-all network of ITD sensitive neurons. Both mechanisms qualitatively accounted for the data, consequently we suggest further experiments based on similar stimuli to distinguish between the two mechanisms. Dietz et al. (2013), “Emphasis of spatial cues in the temporal fine structure during the rising segments of amplitude-modulated sounds,” Proc. Natl. Acad. Sci. 110(37), 15151-15156.