An audio processing chip from Audience has been revealed as the key component behind the dual-microphone noise cancellation technology in the iPhone 4. iFixit reports that the unmarked chip was seen in both the GSM and CDMA iPhone 4, but was not identified as an Audience chip until microprocessor analysis firm Chipworks “decapped” the chip, revealing it as an Audience low power audio signal processor, with an Audience die marking inside.…