His primary area of research involves evoked responses: Measuring electrical responses from the hearing and balance system in response to sensory stimulation. This work can be broadly divided into three areas: 1. Improving the measurement of responses. This includes signal processing approaches (statistical and multi-channel) to better detect the signals in the brain and developing stimulation methods such as chirps and maximum length sequences to better elicit the responses. 2. Exploring the clinical utility of responses. Applications of evoked responses include hearing threshold testing, diagnosis of hearing and balance problems, evaluating the benefit of hearing aids or cochlear implants, and inter-operative monitoring during surgery. These applications are particularly important in patients who cannot co-operate with testing, for example young infants or patients undergoing anaesthesia. 3. Using evoked responses to further understanding of the processing of sound or vestibular input by the brain, for example seeing how connections in the brain alter following cochlear implantation and exploring how attention/ consciousness modulate the processing of sensory information in the brain.
His is also interested in evaluating the benefits of hearing aid and cochlear implant technology, for example by measuring access to sound using evoked responses, or by developing objective approaches to measure the performance of advanced features of hearing aids such as noise reduction or adaptive directional microphones in order to predict the benefit and subjective experience that patients will gain from such devices and has previously researched the effects of mobile phones on hearing.
Much of cochlear physiology and pathophysiology remains poorly understood. For example, how do the 3000 rows of active outer hair cells interact with each other and with other cochlear structures to amplify the waves in the cochlea that allow us to hear? How are the motions of these cochlear structures related to the otoacoustic emissions that we can measure in the ear canal? What role do the efferent nerves play? What are the changes brought about by pathology? The long term research goal is to understand human cochlear physiology in both normal and pathological conditions with a view to aiding the development of improved clinical diagnostic techniques and treatments. One approach to improving our understanding of the electro-mechanical aspect of physiology is to develop realistic models of the cochlea. These should capture the essential hydrodynamics, structural dynamics, and electrical processes involved in cochlear physiology. The non-linear mechano-electrical and electro-mechanical transduction processes are key aspects of the physiology where our understanding remains at a basic level. The ways in which these models may be useful clinically are: to aid the development of treatments, or prostheses for hearing impairment, to improve our ability to interpret clinical results (such as measurements of otoacoustic emissions or electrophysiology), to aid the development of new clinical tests of cochlear function.