Listening to music from which certain frequencies have been removed may ease tinnitus, which affects about 10 million people in the U.S., researchers say.

In a small study, so-called "notched" music therapy significantly reduced the loudness of the ringing in patients' ears compared with the effect on patients who listened to placebo music or had no treatment (P=0.001), Christo Pantev, PhD, of the University of Münster, and colleagues reported online in the Proceedings of the National Academy of Sciences (PNAS).

"The notched music approach can be considered an enjoyable, low-cost, and presumably causal treatment that is capable of specifically reducing tinnitus loudness," the researchers wrote.

Little is known about the mechanisms of tinnitus, but recent studies have shown it may be caused by maladaptive auditory cortex reorganization. In this situation, neurons in the auditory cortex are deprived of normal electrical input because of hearing loss.

Yet the neurons don't become inactive. Instead, they are "rewired" so that they are no longer excited by the frequencies they were originally tuned to. They do, however, become sensitive to neighboring frequencies. That synchronized spontaneous neural activity may lead to tinnitus.

Previous research has shown that this kind of cortical reorganization can be modified by behavioral training.

So the researchers attempted to reduce the loudness of patients' tinnitus by exposing them to music of their choice that was modified, or "notched," to contain no energy in the same frequency range as the patient's tinnitus.

The idea behind this therapy is that the notched music doesn't stimulate the cortical area corresponding to the tinnitus frequency, but it still excites surrounding neurons. Therefore, the neurons that aren't stimulated are suppressed via lateral inhibitory inputs originating from surrounding neurons. The notched music could also have induced synaptic or cellular plasticity mechanisms, the researchers wrote.

They conducted a longitudinal, double-blind study of three groups of patients suffering from chronic, tonal tinnitus. Eight patients had the notched music treatment, eight had placebo music treatment, and seven had no treatment.

The researchers found that after 12 months of regular listening, the loudness of the tinnitus for the eight patients on notched music therapy was significantly reduced compared with that of both groups of controls (P=0.001).

There were no changes in tinnitus loudness in either the placebo group or the no-treatment group.

Notched therapy patients also had reduced activity in areas of the auditory cortex that corresponded to their tinnitus. ASSR and N1m source strength ratios – which represent primary and belt auditory cortex evoked activity, respectively – were significantly reduced after 12 months (P=0.002).

There were no significant differences in these measures for the placebo music or no-treatment groups. The researchers noted that all reduction effects observed in the treatment group were significant after six months.

They concluded that the results "strongly imply that the improvement in the target group reflects a specific treatment effect of custom-tailored target modification of the music."

Source: Kristina Fiore/MedPage Today