Xena Liu is a PhD student in Professor Maria Chait’s lab at University College London. Her PhD studentship began in 2023.
Background
Listening in crowded environments (such as trying to follow a conversation in a restaurant full of people) not only depends on how good your hearing is (how well your ears process sound) but also needs you to use additional cognitive (brain) abilities such as attention and memory. The use of these brain resources during listening is often called “listening effort”.
People with hearing loss have to deploy these additional resources more often, even in less difficult situations (such as talking to a friend in a quiet living room), to compensate for the missing information from their ears. For people with hearing loss, listening effort is greater and often leads to mental fatigue. In some cases, it can cause people with hearing loss to withdraw from social situations.
Understanding listening effort is therefore critical to be able to provide effective treatments for people with hearing loss. It will allow researchers and clinicians to better assess the benefit of interventions such as hearing aids and different hearing aid programmes, to ensure people get the best available help with their hearing loss.
Microsaccades are abrupt, involuntary eye movements that occur when a person fixes their gaze on something, such as a book or a computer screen. Even while the person’s gaze is fixed, their brain constantly creates tiny eye movements to collect information from the surrounding environment.
Evidence suggests that this scanning process depends on a central cognitive resource pool in the brain that is shared with other perceptual processes. If a person’s brain is engaged in a demanding task, such as carrying out a complex maths problem, this depletes the shared resource pool and the rate of microsaccades also decreases.
This suggests that different aspects of perception and cognition (both subconscious and conscious activities) compete for these shared resources, and this could ultimately provide a way to measure listening effort.
Aims
The student will test a new method to monitor microsaccades and investigate how attentive listening affects their rate, direction and extent. They will test the hypothesis that the brain’s computational capacity that is used when listening (the processing resources engaged when a person focusses on listening to something) draws on the same resource pool in the brain as microsaccades. Therefore, if listening becomes harder (for example, if someone is trying to follow a conversation where there is a lot of background noise), this will lead to a reduction in the rate of microsaccades.
To do this, the student will use tasks that assess different aspects of listening in crowded environments. They will test two groups of participants – young (18-30 years old) and older (over 60 years old) to determine whether, and how, auditory attention-linked microsaccade characteristics change with age. Even healthy ageing is associated with attention problems, such as the ability to maintain attention and ignore distractions, that affect someone’s ability to listen in crowded environments.
The student will test whether measuring microsaccades is a useful way to estimate attention and therefore listening effort. If so, they will assess whether it provides useful information to understand the problems with listening attention people have as they age. In the final year of the project, the student will test people with various types of hearing loss who particularly struggle with listening in noisy settings.
Benefit
The findings from this project, if successful, will demonstrate that microsaccades are a useful measure of listening effort. This may provide researchers and clinicians with a cheap, effective way to assess attention and problems with attention (such as those that may arise with hearing loss – if it’s too difficult to listen, then someone will stop paying attention), both in the process of healthy ageing and in various clinical populations where failures of auditory attention are suspected.
Overall, results from the project will provide new practical knowledge about the capacity of microsaccades as a measure of auditory attention and listening effort. This could allow researchers and clinicians to assess listening effort in people with hearing loss and measure the effect of various interventions designed to make listening easier (for example, software programmes in hearing aids designed to reduce background noise).