Apple has hired Dana Massie, a digital signal processing expert from Audience, a company that specializes in audio processing. Their voice processing technology was used in the iPhone 4 and iPhone 4S. Massie has actually previously worked at Apple as a manager, and will be rejoining the company as a system-on-a-chip (SoC) audio architect. At Audience, he was head of digital signal processing chip architecture, according to MacRumors:
While at Audience for the past nine years, Massie was the Director of DSP chip architecture, focused on developing "the most advanced audio processing algorithms available for speech enhancement." Massie also formerly worked at Apple starting in 2002 as the manager of audio hardware. In his year-long stint, Massie was responsible for the audio input/output system on Apple desktops and notebooks.
It's not clear what Massie's exact duties will be, with his expertise lending itself both to possible audio processing improvements in Apple's A-series chips, as well as better voice recognition for Siri.