According to documents obtained by New Scientist magazine under the Freedom of Information Act, the noise level in Zarya is around 72.5 decibels, about the same as a busy street. The Russians recommend astronauts wear ear plugs and spend no more than four hours a day in Zarya. As anyone who lives in an apartment with too-thin walls knows, damping noise is not an easy thing to do. In space, it's even harder. Space and weight are the main constraints on anything and everything that goes aboard a spacecraft, so everything is designed to be as light and as small as possible.
Acoustics are usually an afterthought.
Something hard usually means metal, which adds weight, and sound absorption usually means insulation, which takes up space. According to one engineer who has worked on the problem, NASA is so anxious to cram as much science as possible into the experiments that it's reluctant to take up space for noise control. But NASA engineers are also deeply concerned over the problem. As part of meetings in Moscow discussing the future of Zverda, they are trying to figure out ways of reducing noise aboard the service module, which will serve as the astronauts' living quarters during much of the station's construction. After years of delays, Zvezda is scheduled to be launched this summer.