http://www.brahmand.com/news/Rassvet-noisiest-module-in-ISS-says-station-Commander/4805/1/14.html"All is not so quiet in the International Space Station with the newly installed Russian Mini Research Module (MRM-1), also called Rassvet (Dawn), creating a lot of noise, according to ISS commander Alexander Skvortsov. The module is the noisiest unit of the space station,” Skvortsov said answering a question sent through the ISS Mail Box placed at the Memorial Space Museum for any visitor to send a letter to astronauts."Okay, why is Rassvet so noisy?
Still not sure why. My thought would be circulation fans: they're always noisy.
A new photo of MRM-1's interior, looking from Nadir to Zenith! Hi-res version: www.spaceflight.nasa.gov/gallery/images/station/crew-26/hires/iss026e010223.jpg