Ear bud headphones, even at low volumes, may be causing permanent damage to your hearing.
Researchers at Harvard Medical School's Eaton Peabody Laboratory in the US have found that you can lose up to 90% of your cochlear nerve fibres without losing the ability to detect a tone in quiet environments. But once background noise is introduced, hearing ability drops dramatically. Therefore, the hair cells in the inner ear may be completely intact but hearing is still lost if the nerve synapses are damaged.
Hidden hearing loss
For decades, scientists have looked, almost exclusively, at the loss of hair cells as an indicator of hearing loss. A study released by the Acoustical Society of America however reports a "hidden hearing loss," shedding new light on hearing protection.
The sound waves travel through the middle ear into the cochlea of the inner ear, where they stimulate hair cells. The organ of Corti, inside the cochlea, then transforms the physical motion of the hair cells into electronic pulses for the brain. It's here the discovery has been made.
Ear bud headphones deliver stronger, more damaging waves straight to the cochlea — even at lower volumes. Without a known treatment for cochlear nerve damage, researchers strongly recommend exercising caution.
"Nerve fibres will never reconnect," said Charles Liberman, director of the Eaton Peabody Lab, in the study. "They no longer respond to sound, and, within a few months or years, the rest of the neuron will disappear."
Remember the 60/60 rule
To help slow hearing impairment, it is recommended using over-the-ear headphones instead. They provide a more natural delivery of sound, softening the blow to the inner ear.
Experts also suggest following the 60/60 rule: No more than 60% volume for no more than 60 minutes.