Acoustic stimulation, coupled with nerve electrical stimulation, gives rise to a reorganization of the auditory cortex, in order to reduce extraneous sounds that some people hear all the time.
Researchers at the University of Texas* managed to suppress tinnitus by acting on neural plasticity mechanisms.
They found that people with this disease do not detect a break, at a frequency of about 9 kHz, in a series of sound pulses of 100 Hz to 12 kHz, interrupted each time by one second of silence.
These researchers hypothesised that tinnitus is due to an excess of neurons responding to that frequency, in the auditory cortex.
So they made people hear, several times a day, a range of sound frequencies, except that of the tinnitus, while stimulating the vagus nerve in the neck. After several days of therapy, the result was that patients recovered their ability to detect a break, at a frequency close to that of tinnitus. Neuronal organization had gone back to normal.
Hence the idea of our R & D, to manufacture, in collaboration with a famous lab specializing in hearing disorders, an electronic card which generates a frequency range, except the frequency responsible for tinnitus, synchronous with brief electrical pulses, via an electrode connected to the vagus nerve.
This card, thanks to miniaturization, was integrated into a Vagal Cantar. It is, of course, programmable via a computer, based on many parameters such as undesirable frequency, intensity, silence duration, test beginning... Naturally this unit is operational only when the Cantar is in testing mode! For its part, our software department is currently working on integrating these settings to a new Open Source version of Tarkan. Furthermore we have developed a special Vagal headphone, based on Sennheiser HD 25, which provides, on the minijack connector, besides the two regular wires for loudspeakers, an extra wire connected to a discreet electrode that has to be pasted with gel at the base of the neck. We also have a special Vagal headphone based on Beyer DT 48 for old fashioned sound mixers.
This integration will enable mixers suffering from this terrible handicap to go on working, while receiving a therapy which seems very effective; indeed long waiting periods are not infrequent on a feature film shoot.
The technology used is very discreet, and avoids the usual offensive remarks from the crew "Hey! you're recording like the deaf Beethoven!"
Our first Vagal Cantar so equipped has just gone on the shoot of a remake of "The Silent World". We are waiting for the first reviews of the sound mixer, whose name is being withheld so as not to impair his award-winning career.
* Michael P. Kilgard, Associate Professor, Ph.D., University of California at San Francisco, 1998
Treating Tinnitus by Guiding Cortical Plasticity via Nerve Stimulation