According to the study, a team from the University of Michigan reports the results of the first animal tests and clinical trial of the approach, including data from 20 human tinnitus patients. Millions of Americans hear ringing in their ears, a condition called tinnitus.

As the new study shows an experimental device could help quiet the phantom sounds by targeting unruly nerve activity in the brain. Results of the first animal tests and clinical trial of the approach resulted in a decrease in tinnitus loudness and improvement in tinnitus-related quality of life. This study got published in Science Translational Medicine.

Human participants reported that after four weeks of daily use of the device, the loudness of phantom sounds decreased, and their tinnitus-related quality of life improved. A sham "treatment" using just sounds did not produce such effects.

A dual-stimulus approach to treating tinnitus

The approach, called targeted bimodal auditory-somatosensory stimulation, involves two senses. The device plays a sound into the ears, alternating it with precisely timed, mild electrical pulses delivered to the cheek or neck. But the U-M team's previous work in animals showed that loud noise can trigger a change in the nerve cells' activity altering its timing so that they fire off synchronized signals spontaneously instead of waiting for an actual sound in the environment.

Approximately 15 percent of Americans have some level of tinnitus, but the worst symptoms occur in about 10 percent of sufferers, according to estimates based on interviews with nationally representative samples of Americans. Many of those with more severe tinnitus also have hearing loss.

Current approaches to tinnitus treatment focus include efforts to address the psychological distress it causes, for instance through cognitive behavioral therapy. Other approaches use sound to mask the phantom sounds or attempt to modulate the brain response. For more severe cases, some patients turn to invasive, and therefore riskier, approaches such as deep brain stimulation and vagal nerve stimulation.

The current approach provides a novel and unique, non-invasive strategy that aims to modulate and correct the aberrant neural pathways that cause tinnitus.

Results in human participants

Overall, the loudness of phantom sounds decreased only after the actual, or bimodal, treatment, but not the sham treatment of sound only. For some the decrease was around 12 decibels, about the magnitude of an electric light bulb's hum. Two participants said their tinnitus disappeared completely.

Statistical modeling of the results revealed that, on average, patients experienced significantly reduced scores for the active treatment, though the size of the effect in individual patients varied. On average, scores also stayed lower for weeks after treatment ended. This effect was not significant for the sham treatment.

No patient experienced a worsening of symptoms or quality of life, or other adverse events. Some said their phantom sounds got less harsh or piercing, or became easier to ignore.