Dr Meher Lad

2019 Entry Clinical Fellowship

The Role of Auditory Working Memory in Speech-in-Noice Perception

Hearing loss in midlife is the biggest risk factor for dementia but the reasons for this are unclear. Hearing loss may favour brain mechanisms leading to dementia in some people and studying these may allow us to 1) explain the link between hearing loss and dementia and 2) develop sensitive measures of brain processes leading to dementia.

I studied speech-in-noise perception as a central auditory ability that involves brain pathways implicated in common dementias when an individual has hearing loss. During my 1-year Brain Entry Fellowship I studied how speech-in-noise perception is related to memory for sounds over seconds. Work from our lab has shown that working memory for tones can engage the hippocampus, a brain region implicated in dementias like Alzheimer’s disease. Working memory is a key predictor of speech-in-noise perception when hearing is impaired and I was able to show that working memory ability for simple sounds, such as tones, are better related to the ability of someone to listen to a speaker in a noisy background than other kinds of sounds. Auditory tests for memory involving sounds that are time-invariant may be better suited to probe pathways implicated in hearing loss and dementia.

The fellowship allowed me to gain key skills in organising, interpreting and analysing data from behavioural experiments and developing pipelines for neuroimaging experiments in the future. The work from the fellowship served as key pilot data that enabled me to obtain an MRC Clinical Research Training Fellowship where I will examine how alterations in the structure and function of particular brain structures may influence auditory cognition.