I guess you ask yourself the same question that I asked myself reading about Yamaha developing a heat-resistant microphone for mobile phones. Why do we need a heat-resistant microphone?

The answer is intriguingly simple. The new Yamaha silicon microphone can be easily soldered during the manufacturing process of mobile phones. Handset manufacturers are able to boost production efficiency with this new component.

The Yamaha mic is about 4mm square and 1mm thick.
Yamaha is supposedly working on cell phone microphone chips that will reduce ambient noise.
More details on Nikkei.net (Subscription).