People use their hearing in all sorts of ways and in all sorts of situations. Our sense of hearing helps us to understand what is going on around us, and warns us of unseen dangers. Possibly more importantly, hearing is vital to social communication. For someone with hearing loss, their experience of hearing disability will depend on the mix of social activities they take part in, and the importance they assign to success in those activities. Very little is known about how such patterns of hearing activity differ from person to person, and between people with normal versus impaired hearing. Nor do we know whether using hearing aids changes the activities people take part in. At a more 'microscopic' level of detail, people instinctively behave in certain ways when faced with challenges to their ability to hear. For example, if we cannot hear what someone is saying because of a noisy background, we typically move closer or turn one ear towards them. We know only a little about these behaviours. People with hearing loss face greater challenges than others, and they may use different behaviours, or maybe they could be trained to use more effective behaviours. Meanwhile, hearing aids are generally designed on the assumption that people remain static and face to face, regardless of the situation. This means not only that hearing aids miss out on the chance to take advantage of their wearer's natural behaviours, but that they sometimes undermine the effectiveness of those behaviours. It is becoming increasingly recognised that in order for hearing aids to be more helpful, they must adapt to the moment-to-moment changes in situation which are part of people's everyday life. Furthermore, the clinical prescribing of hearing aids needs to take more account of each patient's individual lifestyle and activity patterns. Our research will provide new knowledge and insights which can form the basis of future improved hearing aid technology and prescribing. We will do this by: - Constructing a mathematical model describing how the acoustics of the environment, hearing impairment, sound processing in hearing aids and body movements all interact to affect people's hearing performance. To do this, we will carry out several experimental studies measuring how people move and change communication tactics when their hearing is challenged. - Determining whether real-world hearing disability (and the relief from disability provided by hearing aids) is driven by isolated events which are crucial for the individual, or by a 'grand average' of events across time. - Devising and testing hearing-aid fitting protocols which account for patients' insensitivity to acoustic changes. - Developing prototype hearing aid technologies which exploit or support listeners' natural behaviour to provide benefits beyond those currently available, and evaluating them in the laboratory and in realistic conditions. - Examining whether routine clinical data can support more individualised prescription of interventions for hearing loss. We will use a very large set of data accumulated as part of routine clinical care, which means the data are relatively loosely controlled. We will evaluate whether known relations are nevertheless reproduced. If so, we will then look for informative new patterns which might be used to improve the individualisation of treatment for hearing problems.