  Astrophysical neutrinos in the EeV range (particularly those generated by the
interaction of cosmic rays with the cosmic microwave background) promise to be
a valuable tool to study astrophysics and particle physics at the highest
energies. Much could be learned from temporal, spectral, and angular
distributions of ~100 events, which could be collected by a detector with ~100
km^3 effective volume in a few years. Scaling the optical Cherenkov technique
to this scale is prohibitive. However, using the thick ice sheet available at
the South Pole, the radio and acoustic techniques promise to provide sufficient
sensitivity with sparse instrumentation. The best strategy may be a hybrid
approach combining all three techniques. A new array of acoustic transmitters
and sensors, the South Pole Acoustic Test Setup, was installed in three IceCube
holes in January 2007. The purpose of SPATS is to measure the attenuation
length, background noise, and sound speed for 10-100 kHz acoustic waves.
Favorable results would pave the way for a large hybrid array. SPATS is the
first array to study the possibility of acoustic neutrino detection in ice, the
medium expected to be best for the purpose. First results from SPATS are
presented.
