Palo Alto startup Sound ID wants to silence that question by outfitting wireless headsets with software used to help the hearing impaired. Its Personal Sound System uses sound-processing algorithms to analyze acoustic environments, so if someone is stuck in a noisy restaurant, the headset instantly boosts the voice signal, separating it from background noise and increasing the volume of human speech by 2 decibels. When the user moves into a quieter room, the levels stabilize. "The system knows which sounds your ear is missing," says Rodney Perkins, Sound ID's founder and chairman.

This fall Sound ID will start selling a Bluetooth headset developed by design firm Ideo. Eventually the technology could be integrated into any cell-phone chip, which explains why Texas Instruments (TXN) was one of several firms to invest a total of $26 million in the five-year-old startup. Sound ID will also sell the Personal Sound System to audiologists to assist patients suffering from mild hearing impairment, a market that could be worth $1 billion a year. Opportunity is calling loud and clear.

By Matthew Majer, Business 2.0