A research team from McMaster University and other universities in Canada and the
United States has pinpointed the source of tinnitus – a phantom and constant ringing in
the ears that affects millions of people worldwide and has a dramatic impact on the quality
of their lives.

In an article published in the latest edition of The Journal of Neuroscience, Larry
Roberts, a professor in the Department of Psychology, Neuroscience & Behaviour at
McMaster, and his co-authors report evidence that the tinnitus sound-described by most
tinnitus sufferers as a constant high-pitched ringing or hissing noise-is generated by
neurons firing in the brain, not the ear.

“Hearing loss associated with noise exposure or the aging process sets the occasion
for the large majority of cases of tinnitus,” he says. “Tinnitus itself is brought on by
changes in the brain that take place when hearing loss occurs”.

Roberts will be part of a symposium presenting ground breaking research on tinnitus
at the Society for Neuroscience meetings in San Diego on November 14.

Other symposium members are Jos Eggermont (University of Calgary), Donald Caspary
(Southern Illinois University School of Medicine), Susan Shore (University of Michigan),
Jennifer Melcher (Harvard Medical School), and James Kaltenbach (The Cleveland Clinic).

Their studies describe how hearing loss modifies the activity of neurons in auditory
pathways and how other brain processes are affected, including those involving the muscle
and skin senses, emotion, and inhibitory functions that change with aging and likely
contribute to tinnitus.

While tinnitus is most common after the age of 60, where 8 to 20 per cent of adults
are affected, chronic tinnitus can occur at any age and is a major cause of service-related
disability in soldiers returning from Afghanistan or Iraq.

“Studies show hearing loss among young people is increasing and we may see an
increase in cases of tinnitus as a consequence of mild hearing losses induced by
recreational sound,” says Roberts. “The implications underscore the need for more public
policy on prevention. Much like the movement that swayed public opinion on the dangers
of cigarette smoking and the need for cessation, we need new initiatives on hearing loss.”