Listening effort and listening fatigue when speaking in noisy environments

COG-MHEAR research is about developing new hearing assistive technology. How will we know if it works well? One way is to measure the effort that people testing the technology are putting into hearing, and the amount of fatigue that this is causing.

Dr Jack Holman of the University of Nottingham is based at the Royal Infirmary in Glasgow. He works to find ways to improve wellbeing of people with hearing loss. He gave a talk to the COG-MHEAR teams about work on listening effort and fatigue. He started by explaining that effort and fatigue are not the same thing. There is the effort that you need to put into hearing in a particular situation; and there is the amount of mental and physical tiredness experienced: fatigue. Many factors influence these. Two different examples would be the need to single out speech from one person in a crowded restaurant; compared with listening to complex language during a presentation at a conference. Each would require effort, and could cause fatigue, but how could these be measured? You could ask someone directly how much effort they are needing to put into listening in different situations. Physiological measurements that are used include changes in heartrate and skin temperature, as well as brain scans. In addition to effort, measurements of pupil dilation could help ascertain the amount of fatigue being caused. Researchers are still finding out which measurements are most representative of experiences, and are the most practical to assess.

Many factors affect responses, including the way you feel that you are managing in a particular hearing situation. The level of motivation that goes into carrying out a task affects the level of fatigue that you feel. Jack gave the example of explaining your work again and again in a crowded room. Fatigue sets in. But then imagine that someone famous that you admire arrives. You are likely to feel much less fatigue as the excitement and motivation of explaining your work changes.

The hearing aids that are being developed in the COG-MHEAR research will be able to pick out one person’s speech in noisy situations. Will listeners prefer to tell them what to do, or will the hearing aids have sensors that can measure the effort that is being put into listening so that they can adjust automatically? The way in which listening effort is measured could be key to the hearing aids working effectively.

Jack Holman’s research is funded by the Medical Research Foundation