Charles Liberman, an established researcher from Harvard Medical School, has written a layman friendly summary of hidden hearing loss in the August edition of Scientific American:
Regarding hidden hearing loss as a potential mechanism of hyperacusis:
“In the past, scientists and clinicians have pointed to the normal audiogram of a tinnitus or hyperacusis sufferer and concluded, again, that the problem must arise in the brain. We suggest instead that the damage may have taken place in the auditory nerve.”
Liberman then goes on to discuss recent research that shows neurotrophins may be a treatment option for hidden hearing loss:
“Hidden hearing loss may soon be treatable by injection through the eardrum of gels that slowly release neurotrophins to restore synapses months or years after a noise insult.”
I encourage reading the full article ($5.99) on the Scientific American website to gain a deeper understanding of hidden hearing loss.