Photo credit: Christina Morillo
by Daniel Fink, MD, Chair, The Quiet Coalition
Are bone conduction headphones safer for your ears? That’s a question that a reader named Bill asked The Naked Scientists website. The answer is simple: “No.” Bone conduction headphones convey sound waves to the inner ear through the bones of the skull, instead of through the external ear canal to the eardrum. Those waves then travel through the middle ear via the oval window, where the sound waves move tiny cochlear hair cells and these movements are transduced into electrical impulses. These in turn are transmitted through synapses (nerve connections) to the auditory nerve, which transmits the impulses to the brain where they are perceived as sound.
Noise damages the cochlear hair cells, causing noise-induced hearing loss. It doesn’t matter whether the impulses are transmitted to the cochlea through the air or through the bone. Too much noise exposure will cause noise-induced hearing loss.
What’s the safe noise exposure level to prevent noise-induced hearing loss? The only evidence-based safe noise exposure level I have been able to find is the Environmental Protection Agency’s level of 70 decibels time-weighted average for a day. Last year I wrote a paper that appeared in the Journal of Exposure Science and Environmental Epidemiology suggesting that the actual safe noise level to prevent noise-induced hearing loss may be much lower, as low as 55 A-weighted decibels* for a single noise event and a daily average of only 55-60 decibels. That’s pretty low.
Preventing noise-induced hearing loss (and most likely tinnitus and hyperacusis as well) is simple and inexpensive. If something sounds loud, it’s too loud and your auditory health is at risk. Turn down the volume, leave the noisy environment, or use hearing protection and your ears should last you an entire lifetime.
*A-weighting adjusts unweighted sound measurements to reflect the frequencies heard in human speech.
