1. A method comprising: determining whether a mobile computing device is receiving operating power from an external power source, wherein the mobile computing device has a trigger word detection subroutine that is activatable by a user input and automatically in response to determining that the mobile computing device is receiving external power; and in response to determining that the mobile computing device is receiving operating power from the external power source, activating a trigger word detection subroutine, wherein the trigger word detection subroutine includes: receiving spoken input via a microphone of the mobile computing device, based on speech recognition performed on the spoken input, obtaining text, determining whether the text includes one or more trigger words associated with a voice command prompt application, and in response to determining that the text includes the one or more trigger words associated with the voice command prompt application, launching the voice command prompt application, wherein the voice command prompt application is configured to receive via the microphone additional spoken input that causes the mobile computing device to launch one or more other applications, and wherein launching the voice command prompt application comprises displaying a voice command prompt on the mobile computing device.
4. The method of claim 1 , further comprising: receiving the user input; and activating the trigger word detection subroutine in response to receiving the user input regardless of whether the mobile computing device is receiving operating power from the external power source.