The Sound of Ice Singing

On the lake called Lissma Kvarnsjö near Stockholm, a brave man skates on new ice that is only a couple of inches thick (45mm). The ice sings and groans and echoes as he glides along. Those who've done this say that the skater doesn't hear much of this, that it takes some distance for the sound to reverberate properly. The eerie sounds are generated by a phenomenon called acoustic dispersion. There's a neat explanation in this video. In case you are simply disappointed that he never fell through the ice, you'll be rewarded by watching this clip.  (via Digg)