1. A computer-implemented method comprising: during a trigger phrase enrollment process: prompting, by a speech recognition-enabled electronic device, a user of the speech recognition-enabled electronic device to speak a trigger phrase; receiving, at the speech recognition-enabled device, a first audio signal corresponding to the user speaking the trigger phrase; determining, by the speech recognition-enabled device, a number of segments in the first audio signal that have voice activity, each segment comprising a corresponding sequence of continuous frames in the first audio signal that have voice activity; and when the number of segments in the first audio signal that have voice activity satisfies a threshold value, training, by the speech recognition-enabled electronic device, a trigger phrase model with the first audio signal corresponding to the user speaking the trigger phrase, the trigger phrase model configured to detect the trigger phrase in a spoken utterance; and after the trigger phrase enrollment process: receiving, at the speech recognition-enabled device and while the speech recognition-enabled electronic device is in a sleep mode, a second audio signal including an utterance of the trigger phrase spoken by the user; and detecting, by the speech recognition-enabled electronic device and using the trigger phrase model trained during the trigger phrase enrollment process, the utterance of the trigger phrase in the second audio signal, the trigger phrase when detected in the second audio signal causing the speech recognition-enabled electronic device to wake from the sleep mode, the sleep mode comprising a power-saving mode of operation in which one or more parts of the speech recognition-enabled electronic device are in a low-power state or powered off.