Distinguished Professor, David Geffen School of Medicine
Auditory Neurophysiology, Mechanics and Behavior My research focuses on the question of how animals extract relevant sounds from the often highly noisy backgrounds in which they live. The techniques I use are the quantitative analysis of vocal behavior of animals in their natural habitats, followed by single fiber neurophysiological recordings in order to elucidate mechanisms underlying signal processing in noise. A second research direction is based on the discovery of the remarkable sensitivity to substrate vibrations possessed by burrowing animals. We are now characterizing and providing accurate measurements of vibrational thresholds as well as exploring the differences between substrate-vibration and airborne sound at the cellular level. Other projects carried out by our group have included an investigation of the neurophysiological basis of sound localization in noisy environments, a study of the temperature-dependence of the representation of time in the vertebrate auditory system, the biophysics of sound localization and the evolution of the middle ear reflex in vertebrates. Current projects include using laser Doppler vibrometry to elucidate the sound pathways relevant for stimulation of both the middle and inner ear in small vertebrates, and using whole-cell voltage clamp techniques to carry out an anatomical and physiological study of the mechanisms underlying transduction in vertebrate sensory hair cells. When possible, we supplement the lab work with direct behavioral observations and controlled acoustic playback studies carried out with animals in their natural habitats. These have included both Old and New World lowland wet tropical forests, African deserts and temperate forests in South America.