Imagine, if you will, that in every room in your house there is a vacuum cleaner -- in fact, imagine that at no point in your life are you ever more than, say, ten feet from a vacuum cleaner -- at work, in the bathroom, the kitchen, the bedroom, the car, everywhere. And further imagine that the vacuum cleaner nearest you is always running, so that at no point in your day can you not hear the sound of a running vacuum cleaner. You must constantly talk to be heard over it. You must turn the TV on loud enough to be heard over the vacuum cleaner, or you must wear headphones cranked high enough to overcome the noise.
This, according to Scientific American, illustrates the noise level on the International Space Station. A running vacuum cleaner produces a sound level of roughly 75 decibels. According to NASA, the worst sound levels in the Station are a consistent 70-72 decibels (in the Russian module), with the levels in the American module in the 50-60 decibel range. The United States Navy, on the other hand, limits regular exposure to ship-board noise over 60 decibels. This is a growing problem for the ISS, as well, because more and more equipment is being taken up and installed.