Effects of lifetime noise exposure on the middle-age human auditory brainstem response, tinnitus and speech-in-noise intelligibility
Date
2018Author
Valderrama, Joaquin
Beach, Elizabeth
Yeend, Ingrid
Sharma, Mridula
Van Dun, Bram
Dillon, Harvey
Metadata
Show full item recordAbstract
Recent animal studies have shown that the synapses between inner hair cells and the dendrites
of the spiral ganglion cells they innervate are the elements in the cochlea most vulnerable to
excessive noise exposure. Particularly in rodents, several studies have concluded that exposure
to high level octave-band noise for 2 hours leads to an irreversible loss of around 50% of synaptic
ribbons, leaving audiometric hearing thresholds unaltered. Cochlear synaptopathy following
noise exposure is hypothesized to degrade the neural encoding of sounds at the subcortical
level, which would help explain certain listening-in-noise difficulties reported by some subjects
with otherwise ‘normal’ hearing. In response to this peripheral damage, increased gain of central
stages of the auditory system has been observed across several species of mammals, particularly
in association with tinnitus.