  South Pole ice is predicted to be the best medium for acoustic neutrino
detection. Moreover, ice is the only medium in which all three dense-medium
detection methods (optical, radio, and acoustic) can be used to monitor the
same interaction volume. Events detected in coincidence between two methods
allow significant background rejection confidence, which is necessary to study
rare GZK neutrinos. In 2007 and 2008 the South Pole Acoustic Test Setup (SPATS)
was installed as a research and development project associated with the IceCube
experiment. The purpose of SPATS is to measure the acoustic ice properties at
the South Pole in order to determine the feasibility of a future large hybrid
array. The deployment and performance of SPATS are described, as are first
results and work in progress on the sound speed, background noise, and
attenuation.
