I have heard a lot of people complain about noisy air pumps, and how they drive them insane. I had this problem too when I first bought and setup my fish tank. I originally bought one of the el cheapo air pumps from walmart, but after the first night of having it setup, I could take the noise any longer.
I went to petsmart, and bought a Rena Air Pump. It wasn’t the cheapest thing, mine was $10.00 for a pump for a ten gallon tank, but the box promised “silent operation.” I took it home somewhat skeptical, but hoping the claim on the box about it being “silent” would be true. When I plugged it in, it was blessed silence to my ears. No humming, vibrating, buzzing, or anything. I’ve had mine for two years now, and it’s still plugging away, as silent as the day I bought it. They also seem to take a beating fairly well. Mine has been dropped I don’t know how many times, but still runs fine. I have never had any problems with it what so ever.
My advice is, you can go to Walmart or someplace like that, and spend $5.00 on one of their air pumps, but more than likely, the noise will drive you crazy. Spend the few extra dollars and invest in a Rena air pump, then sit back and enjoy the silence.