An automatic external defibrillator produces audible prompts for a user by providing the audible information with default audio characteristics in response to a first ambient noise condition and providing the audible information having different audio characteristics than the default audio characteristics in response to a second ambient noise condition. An automatic external defibrillator provides voice prompts by selecting one of a plurality of different levels of sound quality at which to playback the voice prompts and playing back the voice prompts at the selected level of sound quality.
