I think Google is in the lead on this one, with Apple within closing distance but still second.
I might have to revisit what I wrote just yesterday; I wouldn’t discount Intel:
Intel partnered with an unnamed third party to put that company’s voice recognition software on Intel mobile processors powerful enough to parse the human voice but small enough to fit in the device that’s listening, no round trip to the cloud required.
This would be an interesting gumshoe exercise … Nuance?