Sonitus Medical, a company that makes a hearing device to treat single-sided deafness, just brought in $13.5 million in second-round funding to commercialize its flagship product, reports VentureWire. Based in San Mateo, Calif., it still needs to push the device through one more clinical trial and plans to go to market in 2010 if all goes well.

Sonitus’ hearing system consists of two parts: a microphone worn behind the ear, and a component worn inside the mouth that transmits sound via the inner ear. The company is also working on a device to treat tinnitus (chronic ringing, hissing or whistling in the ear), which affects more than two million Americans.

The recent round of capital came from Aberdare Ventures, Novartis Venture Fund and RWI Ventures. Sonitus has raised $18 million to date, which should give it runway until the launch of the hearing aid, the company told VentureWire. It’s currently valued at $33.5 million.