Long ago, almost a year, when the iPhone 4 was officially announced, Apple talked a bit about the two microphones on the device. They were called noise-cancelling microphones, but not much else was said about it. We just knew that this might mean less background noise in our phone calls.
The folks at website iFixit, known for their teardowns, have been able to identify a part of the iPhone that we didn't know about before. It's a little noise cancellation chip by Audience. It wasn't exactly clear what it was when they first cracked open the iPhone 4 shortly after the original release. It was a small 3mm x 3mm chip. It was labeled 10C0 01S8 0077, and it didn't match anything in their database. The same chip was found in the CDMA iPhone 4 (Verizon iPhone 4) and it's down near the A4 processor.
They had Chipworks take a closer look at the chip and they were able to find the Audience die marking inside it:
It's the same processor found in the Nexus One. It uses the two microphones to somehow cancel out ambient noise. We're guessing it has something to do with reversing the polarity or phase of one of the incoming sounds below a certain level.
Either way, the demonstration in the video above is very interesting. You can definitely hear the difference in sound when using a phone that does not cancel noise and when using the iPhone 4, which has the dual-microphone Audience noise-cancelling setup. Perhaps this will become a standard with smartphones moving onward.