For audio files that support loop markers in the file, such as .wav, a useful feature would be a loop mode which plays the selected file up to the end of the loop marker, then loops the audio between the markers. A stop action would be to then play the file past the end of loop marker to the end.
So, for example, you could have single file that includes a machine starting up, a looping section of the machine running designated by markers in the audio file, and then the machine shutting down when the sound is deactivated.
