Preprint · Nov 14, 2025
Objective 1 - Neural Measures - Improving Hearing Aid Outcomes through Brain Stimulation
By Pepper J, Slade K, Plack CJ et al.
On average, it can take around a decade of living with reduced hearing before an older adult receives a diagnosis of hearing loss (Simpson et al., 2019). Reduced signal from the auditory periphery eventually causes atrophy of auditory brain areas (Slade et al., 2022) and makes listening more effortful (McGarrigle et al., 2021). This leads to the reallocation of compensatory brain resources towards listening, and reduces brain resources available for other tasks (Wingfield et al., 2005; Tun et al., 2009; Slade et al., 2020). These brain changes may be one potential reason for why hearing loss is a hypothesised risk factor for dementia (Livingston et al., 2020). Receiving hearing aids may offset some of these maladaptive brain changes (Livingston et al., 2020). Data indicate that hearing aids lead to beneficial neuroplastic changes (e.g. increased N100 amplitude) within two weeks of hearing aid fitting (Karawani et al., 2022), as well as increased cortical thickness being observed in auditory brain areas 12 months after hearing aid receipt (Pereira-Jorge et al., 2018). However, many hearing aid recipients do not wear their aids (Dillon et al., 2020), often due to the hearing aid not providing enough speech clarity to the user (Dawes et al., 2014; McCormack & Fortnum, 2013). As a result, maximising the neural benefit of hearing aids is central to promoting hearing aid uptake, to protect brain health. One way to maximise the neural benefit of hearing aids may be to combine hearing aids with facilitatory brain stimulation to auditory cortex. Transcranial Magnetic Stimulation (TMS) has the potential to catalyse neuroplasticity (Lefaucheur et al., 2020). The benefits of hearing aids could therefore be leveraged by stimulating auditory brain areas with TMS, to increase the neuroplastic potential of the brain when hearing aids are received. This could lead to faster neural benefits from hearing aids and reduce the extent of compensatory neural support. In turn, hearing aids may benefit cognitive function earlier. This research aims to determine whether or not brain stimulation shortly after hearing aid receipt increases the benefits of hearing aids for older adults with age-related hearing loss. Participants will be tested at timepoint 1 as soon as possible (within 8 weeks) after hearing aid receipt, where baseline brain structure (magnetic resonance imaging [MRI]; grey matter volume), brain function (electroencephalography [EEG]; N100 amplitude), auditory (pure-tone audiometry [PTA]; QuickSIN; Speech, Spatial and Quality of Hearing Questionnaire [SSQ]) and cognitive measures (NIH Toolbox, UCLA loneliness scale) will be collected. Participants will then take part in a high-frequency rTMS intervention across a 5-day period (daily sessions Monday-Friday). Specifically, participants will receive intermittent theta-burst stimulation (active TMS group) or sham stimulation (control group) over the left posterior superior temporal gyrus (pSTG) whilst listening to pink noise (to reduce brain state variability across participants and sessions). After the intervention, participants’ brain structure, brain function, auditory and cognitive measures will be collected again (timepoint 2). Finally, participants will return for a final data collection session (timepoint 3), six months after hearing aid receipt, to observe if any TMS-induced changes to brain structure and function, or auditory and cognitive performance, are associated with having received brain stimulation. This project will bring new knowledge of whether the positive impact of hearing aids on the brain can be accelerated by brain stimulation, improving quality of life sooner and protecting brain health. The project has three main aims: 1. To determine if a brain stimulation intervention promotes neuroplasticity in older adults with age-related hearing loss (see Objective 1 preregistration in this OSF project) 2. To determine if a brain stimulation intervention promotes greater audiological benefits from hearing aids (see Objective 2 preregistration in this OSF project) 3. To determine if a brain stimulation intervention is associated with greater cognitive benefits following hearing aid receipt (see Objective 3 preregistration in this OSF project)