What you need to implement is "finite state machine". The moment a button (any button) is pressed, you set the program to the "lights off" state. After some time or when the sound is finished, set it back to the "lights on" state. Switch lights accordingly.
As it's a two-state you could do this with a simple boolean flag.
You may have done this already to prevent button presses from playing a new tone when the previous tone is still playing.