That doesn't sound right. I have the 4000 running a sponge filter on my fry tank... I can barely hear the thing run. It's the quietest air pump I've seen.
"What, exactly, is the internet? Basically it is a global network exchanging digitized data in such a way that any computer, anywhere, that is equipped with a device called a 'modem', can make a noise like a duck choking on a kazoo." - Dave Barry