Understanding Hearing Loss: From Cochlear Function to Gene Therapy and Hair Cell Regeneration

This episode explains how hearing works in the cochlea, why hearing loss is common and impactful, and how it is detected and treated today. It covers UK and global prevalence, signs of loss, and free NHS testing and hearing-aid provision, with a focus on tinnitus as a common cofactor and coping strategies. The science primer explains inner ear biology, the role of outer and inner hair cells in frequency discrimination, and how aging and noise exposure can blunt hearing. The show also surveys emerging therapies, including gene therapy and hair-cell regeneration, that could transform treatment in the future.

Throughout the discussion, listeners hear from Frankie Oliver of RNID about the scale of the problem, and from researchers at the University of Manchester and University of Sheffield about how hearing works and how new therapies might restore hearing.

Introduction and scope

Chris Smith introduces the topic of hearing loss, its prevalence, and the human cost to quality of life, setting up a discussion that blends clinical realities with the science of hearing and emerging therapies.

The scale of the problem

Frankie Oliver of RNID provides the scale: in the UK around 18 million people are affected by hearing loss, deafness, or tinnitus, roughly 1 in 3. The age pattern is striking: about half of those aged 55 have some hearing loss, rising to about 80% in the over-70s. The World Health Organization estimates 1.5 billion people with hearing loss worldwide, potentially rising to 2.5 billion by 2050. A separate concern is the headphone and entertainment noise exposure that puts about 1 billion young people at risk of preventable hearing loss.

“Hearing aids are the gold standard treatment.” - Frankie Oliver

How we hear: cochlear mechanics and neural tuning

Kevin Munro from the University of Manchester explains the cochlea as a snail-shaped structure that sorts frequencies along its length, with high-frequency sounds detected near the base and low-frequency sounds toward the apex. The cochlea also contains outer hair cells that act as amplifiers to sharpen tuning, and inner hair cells that transmit signals to the auditory nerve. With two ears, humans gain spatial hearing, helping us localize sound in noisy environments.

“Outer hair cells act as amplifiers, boosting the sound inside the cochlea.” - Adam Carlton

Diagnosing and treating hearing loss

The discussion moves to pure-tone audiometry, a test that maps the quietest sound a person can hear across frequencies, guiding whether a conductive or sensorineural problem is present. In the NHS context, hearing tests and digital hearing aids are widely available. Conductive losses, such as a perforated eardrum, may be addressed mechanically, while sensorineural losses due to hair-cell damage present greater challenges for restoration. Tinnitus is discussed as a common companion to hearing loss, often mitigated by amplification and therapy.

“The brain is turning up the amplifier to hear,” - Adam Carlton

The tinnitus conundrum and management

There are two flavors of tinnitus: a real perceptual sound and neurologically generated phantom sounds. The podcast explains central gain as a brain-driven amplification when auditory input is reduced, contributing to tinnitus after hearing loss. Management strategies include cognitive behavioral therapy, relaxation, sound therapy, and emerging non-invasive neuromodulation approaches as research advances.

Emerging therapies: gene therapy and hair cell regeneration

Konstantina Stanovic discusses the frontier of treating inherited deafness with gene therapies delivered to the inner ear and approaches to hair-cell regeneration. Gene therapy can address missing or dysfunctional proteins essential for neurotransmitter release, with early-stage trials showing safety and sometimes striking improvements. In parallel, researchers are uncovering molecular pathways that could enable hair-cell regeneration in mammals by reactivating developmental programs, reprogramming supporting cells, and using epigenetic modification or drug cocktails. Birds and reptiles, which spontaneously regenerate hair cells, provide crucial clues for translating these mechanisms to humans.

“Autoflin is a protein which is required for neurotransmitter release, and gene therapy trials have demonstrated sometimes remarkable success and definitely early safety.” - Konstantina Stanovic

Outlook and conclusion

While still largely in the research domain, the path to practical therapies involves parallel exploration of gene therapy, hair-cell regeneration, and related devices. Mammals have the necessary supporting cells, and progress in mice offers a hopeful glimpse of the future where hearing loss could be significantly improved or reversed. The discussion ends with a sense of cautious optimism about the coming years and the broader implications for science funding and responsible innovation.