Dag Kittlaus — the co-founder and CEO of the company that created the Siri voice control feature, which Apple launched along with the iPhone 4S, has left the company, though the departure was “amicable,” according to “AllThingsD” (http://macte.ch/ifreU).

Quoting unnamed sources, the article says there were several reasons for the departure, including Kittlaus’s family being in Chicago, a desire to take time off and an interest in brainstorming new entrepreneurial ideas. Kittlaus has led the speech recognition efforts for Apple since Apple bought Siri in April of 2010.

Siri on iPhone 4S lets you use your voice to send messages, schedule meetings, place phone calls, and more. Apple says that you can ask Siri to do things just by talking the way you talk. I haven’t tried it, but Apple says Siri understands what you say, knows what you mean, and even talks back.

What differentiates Siri from competing technologies is its ability to not only recognize words spoken in a normal tone of voice, but its capacity to pick up on the contextual meaning of a phrase, according to Apple.