Alert: poor english onward.
Have a Command Node deep in creeper and enable the sound warning.
While the sound is playing press one of the WASD keys and the sound will abruptly interrupt.
I haven't found any other key that causes the same effect.
Sure enough.... seems so weird and impossible.
But, that particular sound was imported improperly and was set to be a "3d" sound in unity's import settings.
Will be fixed in the next build (coming in a couple weeks).