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Low-pitch treatment alleviates ringing sound of tinnitus

February 15, 2007

For those who pumped up the volume one too many times, UC Irvine researchers may have found a treatment for the hearing damage loud music can cause.

Fan-Gang Zeng and colleagues have identified an effective way to treat the symptoms of tinnitus, a form of hearing damage typically marked by high-pitched ringing that torments more than 60 million Americans. A low-pitched sound, the researchers discovered, applied by a simple MP3 player suppressed and provided temporary relief from the high-pitch ringing tone associated with the disorder.

Tinnitus is caused by injury, infection or the repeated bombast of loud sound, and can appear in one or both ears. It's no coincidence that many rock musicians, and their fans, suffer from it. Although known for its high-pitched ringing, tinnitus is an internal noise that varies in its pitch and frequency. Some treatments exist, but none are consistently effective.

Zeng presented his study Feb. 13 at the Middle Winter Research Conference for Otolaryngology in Denver.

"Tinnitus is one of the most common hearing disorders in the world, but very little is understood about why it occurs or how to treat it," said Zeng, a professor of otolaryngology, biomedical engineering, cognitive sciences, and anatomy and neurobiology. "We are very pleased and surprised by the success of this therapy, and hopefully with further testing it will provide needed relief to the millions who suffer from tinnitus."

As director of the speech and hearing lab at UCI, Zeng and his team made their discovery while addressing the severe tinnitus of a research subject. The patient uses a cochlear implant to address a constant mid-ranged pitched sound in his injured right ear accented by the periodic piercing of a high-pitched ringing sound ranging between 4,000 and 8,000 hertz in frequency.

At first, Zeng thought of treating the tinnitus with a high-pitched sound, a method called masking that is sometimes used in tinnitus therapy attempts. But he ruled out that option because of the severity of the patient's tinnitus, so an opposite approach was explored, which provided unexpectedly effective results.

After making many adjustments, the researchers created a low-pitched, pulsing sound - described as a "calming, pleasant tone" of 40 to 100 hertz of frequency - which, when applied to the patient through a regular MP3 player, suppressed the high-pitched ringing after about 90 seconds and provided what the patient described as a high-level of continued relief.

Zeng's patient programs the low-pitched sound through his cochlear implant, and Zeng is currently studying how to apply this treatment for people who do not use any hearing-aid devices. Since a cochlear implant replaces the damaged mechanism in the ear that stimulates the auditory nerve, Zeng believes that a properly pitched acoustic sound will have the same effect on tinnitus for someone who does not use a hearing device. Dr. Hamid Djalilian, a UCI physician who treats hearing disorders, points out that a custom sound can be created for the patients, who then can download it into their personal MP3 player and use it when they need relief.

"The treatment, though, does not represent a cure," Zeng said. "This low-pitch therapeutic approach is only effective while being applied to the ear, after which the ringing can return. But it underscores the need to customize stimulation for tinnitus suppression and suggests that balanced stimulation, rather than masking, is the brain mechanism underlying this surprising finding."

Qing Tang, Jeff Carroll, Andrew Dimitrijevic and Dr. Arnold Starr of UCI; Leonid Litvak of Advanced Bionics Corp.; and Jannine Larkin and Dr. Nikolas H. Blevins at Stanford University participated in the study, which was supported by the National Institutes of Health.


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