Hi there
Likely the best way to do this is by defining Advanced Actions to play the audio. But if you want to try sticking with simple buttons, perhaps enable the Success Captions for each button. Then assign the audio to the Success Captions. These should only show once for each button and should not trigger the multiple audio.
You would configure the Success Captions so there is no text and they are the Transparent caption type.
Cheers... Rick 