My research is broadly-based in hearing and speech, with an emphasis on the interface between the two. Over the years I have studied a variety of aspects of auditory perception (speech and non-speech) in adults and children, both in disordered and normal populations. I initially came to UCL to work on cochlear implants, and some of my work still concerns this. I have long been interested in the adaptation of cochlear implant users to their new kind of hearing. Incomplete electrode insertion means that patients experience an upward spectral shift in auditory information, and there have been claims that this may be crucial in limiting implant patient performance. Our team was the first to show that people can adapt readily to such spectral shifts, with many further studies both concerning cochlear implants in particular, but also the nature of perceptual adaptation.

I also spent many years investigating some of the most basic aspects of auditory processing, and our group developed a simple description of auditory filtering as a function of level that clarified the nature of the essential non-linearity both in normal and impaired hearing. My current interests in this area are more concerned with other decompositions of auditory information, in particular into fine-structure and envelope information. I proposed a classification of the temporal properties of the speech wave some years ago, and I am still developing various aspects of it. I have also become interested in a physiological measure of relatively low-level auditory functioning, the Frequency Following Response, and its possible use in diagnostics. A major theme of much of my work concerns the perception of speech in the presence of other sounds, and the mechanisms involved in both normal hearing and hearing impaired listeners.

Over the last 20 years, much of my work has shifted focus to more central auditory processes. I have been involved in studies of functional brain imaging (fMRI, fNIRS, EEG and PET), in attempts to determine the neural substrates for speech and nonspeech processing. I have also been investigating auditory processing in people with specific language impairment and dyslexia, arguing that although auditory processing deficits appear to be more common in such groups, they do not appear to play a causal role in the language deficits. Related work concerns the notion of Auditory Processing Disorder (APD) in children, and its implications for development.