This information isn’t particularly relevant to anyone outside the rarefied field of chip nerds and those curious about what their iPhones are made of — and possibly Apple’s competition. The chip involved, for instance, was “white labeled,” meaning that the normal branding and manufacturing information was not printed on it (as you can see in photos published by iFixIt), a technique sometimes used to obfuscate the origin of licensed chips.
When ChipWorks decapped the chip (which means they were able to open it up), however, they found an Audience embedded digital signal processor. That means that this is the technology used to provide in-iPhone noise cancellation for the outgoing signal.
In the video below, you can hear a side-by-side comparison of a call from a noisy environment from an iPhone 4 and another unidentified “typical cellphone” (the iPhone 4 is the second phone call in the recording) posted to YouTube. That difference is made possible by the Audience chip.
“Typical Cellphone” vs. iPhone 4 in a noisy environment