Last summer, when the folks at iFixit first did a tear down of the iPhone 4, one of the interesting tidbits they revealed was that the iPhone 4 has two mics (which is more than most other cell phones), and that it has a white-labelled (manufacturers details removed upon request from Apple) noise cancellation chip in it. The idea being that ambient noise is identified by the second mic, and processed and cancelled out by the chip -- leaving the person listening to whoever is speaking into the iPhone 4 with much clearer audio.
Furthermore, a few months ago, you may have noticed that iFixit -- along side the help of Chipworks -- revealed the unbranded chip to be a low power audio signal processor manufactured by Audience. The same noise cancellation chip found in the Google Nexus One phone.
While that in itself may not be all that interesting, we thought you may be interested in the YouTube video iFixit sourced to demonstrate the power of the Audience chip. The video below is a recording of two separate voice mail messages called from the same noisy location, but on two different phones. One is from an unnamed, standard cell phone, the other is from the iPhone 4.