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 an important part of my current work still concerns this. One strand concerns the optimisation of the transmission of voice melody information in multi-channel implants and a current project for optimal combination of electrical stimulation in one ear with residual hearing in the other (drawing heavily on the expertise developed concerning the auditory processing of people with profound hearing impairment). A separate offshoot of this work concerns 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 spent many years investigating some of the most basic aspects of auditory processing and consideration of the auditory filtering properties of hearing-impaired listeners led our group to the development of a simple description of auditory filtering as a function of level that clarified the nature of the nonlinearity 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 more than 15 years ago, and I am still developing various aspects of it. Over the last 10 years, much of my work has shifted focus to more central auditory processes. I am involved in studies of functional brain imaging (PET and fMRI), 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 and its implications for development.