Evidence has also emerged that the auditory nerve
fibres connecting to the hair cells may also be damaged over time by noise exposure.
Born without working auditory nerves
, she can detect sounds for the first time -- and start to mimic them -- after undergoing brain surgery to implant a device that bypasses missing wiring in her inner ears.
Dr Helmy Mulders, who led the research, said: "Studies in human tinnitus sufferers are still needed to confirm our results and to establish whether or not this approach will be effective for people who have had tinnitus for a long time, but our research shows that lowering the activity of the auditory nerve
may be a promising approach to treating recently triggered tinnitus.
This implant included a long, flexible electrode, which could, for the first time, deliver electric signals to the auditory nerve
along a large part of the cochlea, the snail-shaped inner ear.
He explained, "Hearing aids only amplify sounds, but cochlear implants bypass damaged portions of the ear and directly stimulate the auditory nerve
The fluid in the cochlea causes the hair cells to transmit electrical signals via the auditory nerve
to the brain, where these signals are processed as sound.
The topics include the physics and analysis of sound, the auditory nerve
, mechanism of transduction and excitation in the cochlea, the auditory cortex, and sensorineural hearing loss.
We showed that the sheath around the auditory nerve
is lost in about half of the cells we looked at, a bit like stripping the electrical cable linking an amplifier to the loudspeaker.
As shown schematically in the Figure, the ascending central auditory pathways begin with the termination of the auditory nerve
at the cochlear nucleus and extend through the brainstem, thalamus, and corpus callosum before terminating in the primary auditory cortex, located in the superior temporal gyrus.
One convincing piece of evidence: Past attempts to cure the condition by severing the auditory nerve
in desperate patients left people completely deaf to the outside world--but didn't silence the ringing.
The sounds are converted into electrical impulses and sent to the auditory nerve
, which carries the signals to a person's brain where they are translated into recognizable sounds.
The device bypasses damaged or diseased parts of the ear by directly stimulating the auditory nerve
, which is connected to the brain.
It converts sound from a small microphone into electric impulses that the auditory nerve
reads as sound.
These may include hearing aids fitted to match the unique hearing loss of the child, or in cases of severe to profound hearing loss a cochlear implant that electrically stimulates the auditory nerve
in response to sound.
Thirteen-month-old Dylan Harrison, from Solihull, has a condition which causes him problems with his sight and hearing, which means he has to wear a hearing aid in one ear and has no auditory nerve
in the other.