image: Three features were used to predict hearing level (D): auditory nerve fibers (A), stria vascularis (B), and hair cells (C).
Age-related hearing loss has more to do with the death of hair cells than the cellular battery powering them wearing out, according to new research in JNeurosci. That means wearing ear protection may prevent some age-related hearing loss.
Every day, people subject their ears and the delicate hair cells -- the cells inside the cochlea that turn sound waves into electrical signals -- within them to damaging noisy environments and too-loud headphones. However, ears also age. Both the hair cells and the stria vascularis, the cellular battery powering them, degrade with age. For 60 years, scientists attributed noise-induced hearing loss to hair cell death and age-related hearing loss to stria vascularis damage. But a new study from Wu et al. proves otherwise: age-related hearing loss in humans stems from hair cell death, not stria vascularis damage.
The research team counted surviving hair cells, auditory nerve fibers, and stria vascularis area in cochlea samples from 120 people and compared the damage to hearing test scores. Hair cell death predicted the severity of hearing loss, while stria vascularis damage did not. This contradicts findings in animal models, where the opposite is true. But animals do not experience the same auditory abuses as humans, which may mean that much of age-related hair cell loss is noise-induced, and therefore avoidable.