Quasinormal Ringing for Acoustic Black Holes at Low Temperature
  We investigate a condensed matter ``black hole'' analogue, taking the Gross-Pitaevskii (GP) equation as a starting point. The linearized GP equation corresponds to a wave equation on a black hole background, giving quasinormal modes under some appropriate conditions. We suggest that we can know the detailed characters and corresponding geometrical information about the acoustic black hole by observing quasinormal ringdown waves in the low temperature condensed matters. 
Hiroyuki Nakano, Yasunari Kurita, Kouji Ogawa, Chul-Moon Yoo