The ASHA Leader, May 2015, Vol. 20, 13. doi:10.1044/leader.RIB2.20052015.13
Ears may protect against tissue damage from loud noises using a unique defense mechanism, suggests research from Northwestern University.
The study, conducted on mice and published in Current Biology, points to a possible pain system—a pathway discrete from that used to hear everyday sounds—thatconnects the cochlea to the brain. Researchers call the pathway’s function “auditory nociception,” and suggest it could operate much like nerves that alert a person to different types of pain, such as touching a hot stove. The human inner ear does not have this type of nerve.
The pathway could help researchers better understand and develop treatments for painful conditions such as hyperacusis and tinnitus.
“If we find they are actually pain syndromes rather than hearing syndromes, perhaps they could be treated effectively with analgesic pain medication,” says Jaime García-Añoveros, senior author of the study.
In the pathway, noxious, damaging levels of noise activate a single set of neurons—a possible reason we reflexively plug our ears around loud noise. The reaction may also stiffen inner ear muscles to cut down on noise allowed through. However, it’s unclear what triggers the neurons: the death of hair cells or the dangerous sounds.
García-Añoveros believes his team will find a human equivalent of the pathway in future research.
© 2015 American Speech-Language-Hearing Association