Phonon tunnels from a sonic black hole
  We investigate the phonon radiation from a spherically symmetrical, stationary, viscid-free son-ic black hole by using a semi-classical method. The backreaction of the radiated phonon is taken into account. We obtain the phonon emission temperature, and it is consistent with the Hawking's formula. 
Hengzhong Fang, Kaihu Zhou
gr-qc