A method is disclosed for generating a voice-activated responsive action, such as a pulse or a measurement, with improved speed and time resolution. First, an operator calls an arming command to prepare the application, and then calls a trigger command to initiate the responsive action. The responsive action is generated immediately upon detecting the leading edge of the trigger command, resulting in an extremely fast response with precise timing. The particular responsive action may be determined by the type of sound detected, or by other information contained in the trigger command, or by the arming command, or by another prior command. Other types of preparatory events are disclosed. Efficient methods for identifying commands are disclosed. For all applications requiring an extremely prompt, precisely timed, hands-free response to a voice command, this invention is enabling.