My goldfish are making alot of noise! Grrrr?

I have a tank in my room with 4goldfish 5feederbarbs and 1brislenosecatfish. They are all frys. Of a night I hear a small tap sound and I've figured out its bubbles and panda playing with the rocks. (they can't swallow them or the rocks can't get stuck) what can I use to plug my ears that is safe to use during sleep.? (I roll alot in sleep)