ARI Guest Talk: 27.06.2024
Sensitivity to interaural time and level differences—ITDs and ILDs, respectively—underpins the ability to locate sound sources. It is common to explore these binaural cues in isolation, focussing on ITDs conveyed in the temporal fine structure of low-frequency sounds, and ILDs (and envelope ITDs) conveyed in the (modulated) energy of high-frequency sounds. However, real sources in real environments contain these elements simultaneously, including within the same frequency bands, and it is likely that the brain evolved mechanisms to exploit this information to promote survival. I will demonstrate evidence suggesting that performance in spatial listening tasks 1) strongly depends on ITDs conveyed in rising (and sometimes falling) sound energy—listeners are insensitive to ITDs conveyed during peak energy, and 2) relies on neural mechanisms that enhance the representation of energy modulations. In noisy listening environments, these mechanisms likely support the generation of internal ‘neural envelopes’ that enable sources to be heard out in otherwise diffuse backgrounds.
David McAlpine trained at the University of Western Australia, where he undertook his Honours (Diplom) with Professor Brian Johnstone in cochlear mechanics. Following graduate studies at Oxford University with Professor David Moore, he undertook his post-doctoral research with Professor Alan Palmer at the MRC Institute of Hearing Research in Nottingham. He moved to University College London in 1999, first as a Lecturer, Reader, and then Professor of Auditory Neuroscience, where, from 2006-2015, he was also the inaugural Director of the UCL Ear Institute. In 2015 he moved to Sydney, Australia as Professor of Hearing, Language, and the Brain at Macquarie University where he leads the University’s hearing initiative at the Australian Hearing Hub—home also to Cochlear Ltd and the National Acoustic Laboratories. His main research interest in binaural hearing—from biophysics to behaviour—has transformed our understanding of how auditory space is represented in the mammalian brain.