An external medical device such as a wearable defibrillator can include a housing, an energy storage module within the housing for storing an electrical charge, and a defibrillation port within the housing for guiding via electrodes the stored electrical charge to a person. The medical device can also include a processor within the housing configured to control a voice prompt customization module, in which the voice prompt customization module allows a programmer to customize voice prompts, and a user interface configured to deliver at least one voice prompt customized by the programmer
