Hearing begins as physics but is shaped by experience. The brain doesn't simply receive sound - it learns how to interpret it, using brain plasticity to map voices in space, filter noise and make sense of the auditory world, much like learning to navigate busy city streets. When hearing falters, the breakdown can occur anywhere along that pathway, from the delicate structures of the inner ear to the brain's learned ability to organize sound.
At Western University, investigators in the National Centre for Audiology (NCA), led by professor Susan Scollie, are driving innovation. Researchers in the NCA's 16 interdisciplinary labs work across the hearing spectrum, from improving early screening for infants to enhancing patient care to strengthening evaluation of hearing technologies.
Two Western scholars are tackling problems at different stages of the hearing process. Surgeon-scientist Dr. Sumit Agrawal is restoring hearing at its source inside the cochlea, while neuroscientist Ingrid Johnsrude studies how the brain interprets sound in a noisy, ever-changing world. They share a common goal: repairing not just the ability to detect sound, but the full human experience of hearing.
Advancing cochlear implants using AI
At the intersection of surgery, engineering and artificial intelligence, Agrawal is reshaping how doctors understand and ultimately restore hearing. His research focuses on the cochlea, the spiral cavity of the inner ear where cochlear implants translate sounds into electrical signals for the brain to process as sound.
Cochlear implants have returned hearing to hundreds of thousands of people worldwide, yet outcomes vary widely from one patient to another. One reason is that conventional medical imaging cannot clearly reveal the delicate internal anatomy where implant electrodes must be placed and later programmed.
To address that challenge, Agrawal partnered with Hanif Ladak, professor of engineering and medical biophysics, to establish Western's Auditory Biophysics Laboratory. Here, Agrawal, Ladak and their team are training AI systems to reconstruct the cochlea's hidden anatomy from standard CT scans. By giving surgeons a detailed map of each patient's inner ear, their approach improves not only the precision of surgery, but the post-operative mapping and tuning of the implant as well.
"Hearing connects us to language, to music, to each other," said Agrawal, chair of otolaryngology - head and neck surgery at Western's Schulich School of Medicine & Dentistry and department head at London Health Sciences Centre and St. Joseph's Health Care London. "If we can tailor treatment to every individual, from surgery to programming, we can give patients not just hearing, but a richer way of experiencing the world."
Dr. Sumit Agrawal reviews a customized cochlear implant designed to improve hearing for patient Taryn Armstrong. (Western Communications)
Strengthening sound cognition in everyday environments
Restoring hearing, however, is only part of the challenge. Once sound reaches the ear, the brain must still interpret it. That's where Johnsrude's research begins.
Early in her career, she and her collaborators demonstrated the brain's remarkable ability to change with experience. In a landmark study, they showed brains of taxi drivers in London, England physically changed after years of navigating the city - evidence that regions involved in spatial memory can grow with demanding cognitive tasks. The finding helped reveal the power of brain plasticity.
Today, Johnsrude studies how the brain interprets sound in the complex environments people encounter every day: busy restaurants, crowded streets and overlapping conversations.
She recreates those challenges with realistic soundscapes in Western's Audiodome, an innovative spherical chamber containing 91 independent speakers. By controlling where sounds originate and how they interact, researchers can study how listeners track voices, locate people speaking and filter noise.
"Listening rarely happens in silence," said Johnsrude, a clinical neuropsychologist and chair of Western's department of psychology. "If we want to understand hearing, and help people who struggle with it, we have to study how the brain works in the real acoustic world."
This article has been re-published with permission from The Globe and Mail.
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