  We present development work aiming towards a large scale ice-based hybrid
detector including acoustic sensors for the detection of neutrinos in the GZK
range. A facility for characterization and calibration of acoustic sensors in
clear (bubble-free) ice has been developed and the first measurements done at
this facility are presented. Further, a resonant sensor intended primarily for
characterization of the ambient noise in the ice at the South Pole has been
developed and some data from its performance are given.
