how long is the actual sound? are the button presses only going to play part of the sound up to a certain point?
you are most likely going to be looking at the Audio object and "pausing" based on Audio.PlaybackTime("Tag")
https://www.scirra.com/manual/109/audio
or you could simply set off a Timer for however long you want the audio to go, and then Audio>Set Paused "tag", then Set Pause again to resume (on Button press).
https://www.scirra.com/manual/167/timer