Kulturtechno

Dirk Rothbrust, Schlagzeuger vom Ensemble Musikfabrik, hat einen merkwürdigen Glissando-Effekt bei seiner Kaffeetasse beobachtet, wie er in dem Video zeigt.

Dank Twitter-Umfrage ist die Lösung gefunden – hier handelt es sich um den Hot chocolate effect. Wikipedia:

The Hot Chocolate Effect is a phenomenon of wave mechanics first documented in 1982 by Frank Crawford, where the pitch heard from tapping a cup of hot liquid rises after the addition of a soluble powder. It typically arises in the making of hot chocolate or instant coffee, but also occurs in other situations such as adding salt to supersaturated hot water or cold beer.
[…]
The phenomenon is explained by the effect of bubble density on the speed of sound in the liquid.

(via MusikFabrik Blog)