15. The computer-implemented method of claim 1 wherein determining whether to switch from a current mode of operation to a second mode of operation includes determining whether to switch from a current mode of operation during which the mobile computing device does not monitor ambient sounds for voice input that indicates a request to perform an operation.
16. The computer-implemented method of claim 15 including determining, based on the current context, whether to switch from the current mode of operation to a second mode of operation during which the mobile computing device selectively monitors ambient sounds for voice input that indicates a request to perform an operation.