The acoustic experience of nordic ice-skating
There is a laser-like symphony of sounds that comes from the ice.
Henrik Trygg and Mårten Ajne are two Swedish ice skating enthusiasts who showed us this art.
In this video Trygg filmed Ajne skating on 45-millimeter-thick ice on Lissma Kvarnsjö, a lake outside Stockholm, Sweden.
They look like athletes, but what is required to thin-ice skating is a scientific brain.
Engineers, mapmakers, and mathematicians, they are the kind of people who can handle this particular challenge.
Skating on black ice of about 3.5 centimeters involves a lot of preparation, math calculations, checking the atmospheric conditions, looking at satellite images and the smoothness of the surface.
But what is really catchy is the alien sound that the black ice produces.
The two skaters explain this effect to the National Geographic magazine:
“In the video, the sounds are created by me (Ajne) skating on it. There is a distinctive sonorous tone and the noise from cracks striking.
Black ice doesn’t expand and contract because it’s kept warm by the underlying water, even when it’s cold out. Isothermal would be the technical word for it—in a narrow temperature range.
The sonorous tone is the song of black ice, best heard (and recorded) from a short distance. The layman explanation would be that the tone is inversely related to the thickness of the ice.
The thinner the ice, the higher the tone.
Intriguingly, the ice is about to collapse at high C, the supposedly highest note of a soprano opera singer, for example in Puccini’s Turandot.”
