The ear is the only one of our five senses capable of detecting signals embedded in a background of noise (see Hudspeth, 1997). The role of the outer and middle ear in setting this auditory sensitivity remains unclear, while it seems that the cochlea acts to enhance signal detection by an internal amplification process that is frequency-specific but, as yet, not well understood (see Dallos et al. 2006, Chan & Hudspeth, 2005). Concomitant with this internal amplification process in the cochlea is sound radiating out of the ear, or otoacoustic emissions, that provide a non-invasive window into cochlear mechanical function (e.g., Shera & Guinan, 2007). My research focuses on the biophysics of the mammalian ear, the goal being a better understanding of how the mechanics of the ear set auditory sensitivity. My current investigations include

• the role the outer and middle ear have in setting in auditory sensitivity
• the mechanisms of generation of otoacoustic emissions
• the role hair cell damage plays in Presbycusis
• cochlear tuning in mammals
  

Perception is a biological process. The sensations and perceptions associated with any sensory system arise through a series of neurobiological events. The process begins in the periphery with the transduction of the physical stimulus into neural impulses and ultimately ends with the recognition of the stimulus by the organism. I am interested in understanding how the physical features of complex sounds are encoded or represented in the auditory nervous system and how these representations are then related to the perceptual attributes of the sound.

To address these issues, my research program is directed along three lines of investigation.

• Conduct psychophysical experiments in human listeners to define the perceptual attributes and detection/discrimination thresholds for a set of complex sounds. How does behavioral performance or perception change as a specific acoustic feature changes systematically?
• Conduct similar psychophysical experiments using operant-conditioning in chinchillas to the same types of sounds. Again, how does behavioral performance change as a specific acoustic feature changes systematically? What are the perceptual differences and similarities between humans and chinchillas?
• Record the activity of single neurons in the chinchilla auditory system in response to the same types of complex sounds. How do the neural representations encoded in firing rate and temporal discharge patterns change as a specific acoustic feature changes systematically?