Both use simple earbuds that transmit messages to the brain that change the way it 'hears' sounds.
The first, a technology known as bimodal auditory-somatosensory stimulation, has been tested by researchers at the University of Michigan on a small group of tinnitus sufferers. After using the technology 20 minutes a day for 25 days, the 20 sufferers all reported a significant improvement; some said the noises they heard were 12 decibels softer, others said the noises were less harsh or piercing, and two reported their tinnitus had disappeared. None of these improvements were reported by another group of tinnitus sufferers who had been given a sham treatment.
The technology works by changing the way the brain 'hears' in a process known as long-term depression (LTD) in nerve activity that contributes to tinnitus. In healthy people, the nerves—known as fusiform cells—help locate where sound comes from, but become over-active in the tinnitus sufferer, usually after they have been damaged, such as when they have been exposed to loud noises.
Bimodal auditory-somatosensory stimulation plays sounds into the ear that match the frequency and volume of the whistling and rushing noise of tinnitus.
In a separate trial, researchers have been eliminating tinnitus by using neuro-feedback technology that trains the brain to focus on different sounds and sensations. The basis of the technique is the understanding that there is a close relationship between 'hearing'—the way the brain picks up sounds through the primary auditory cortex—and other processes that monitor breathing or touch, for instance.
By shifting the focus, the sounds of tinnitus can be reduced or even reversed, say researchers from Wright State University in Ohio. They tested the theory on a group of 18 healthy people, who were fed 'white noise' through earplugs while an MRI scanner was monitoring their brains.
The researchers hope that biofeedback could also be developed to help people cope with pain.