Manchester has completely ground to a halt with heavy snowfall. Yesterday, my children and their friends built an impressive igloo from compacted snow bricks. I crawled into it this morning and was struck by the sound of my voice inside. Normally in a small room your voice gets enhanced by the sound bouncing around the room – this is why people think they sound so great when they sing in the shower. But in the igloo it was just very dead, nothing was reflecting from the walls and the room wasn’t distorting my voice. This happened because snow efficiently absorbs sound .
Snow also changes the sound of the streets. In normal life we are used to unconciously hearing sound reflecting off the road and pavement. With large amounts of snow on the floor the ground reflection is removed and you suddenly begin to notice other subtle effects such as the sound echoing off building facades.
It has been suggested that a proper igloo has the insides of the walls sealed by partially melting the snow and allowing it to refreeze. But if we did that, then acoustic effect would disapper.
 T. Iwase, T. Sakuma and K. Yoshihisa: Measurements on sound propagation characteristics in snow layer, Proc. 17th ICA (Rome), 1, 274-5, (2001).