Why do some Android phones have two microphones instead of one? Some phones such as the Samsung Galaxy SIII have two microphones, one next to the user's mouth which as is the case with most mobile phones, but also a second microphone next to the user's ear. Other models such as the Samsung Galaxy S Plus only have one microphone.

What are the advantages of having two microphones on a mobile phone device?

Thanks.
The second microphone is used for noise cancelling. The phone uses it to listen to the external environment (not including your voice), so that it can filter that out from the sounds it hears using the main microphone. That way, it can reduce the amount of noise that comes with your voice, and make your call more audible to the other party.