Using the South Pole Acoustic Test Setup ( SPATS ) and a retrievable transmitter deployed in holes drilled for the IceCube experiment , we have measured the attenuation of acoustic signals by South Pole ice at depths between 190 m and 500 m. Three data sets , using different acoustic sources , have been analyzed and give consistent results .
The method with the smallest systematic uncertainties yields an amplitude attenuation coefficient \alpha = 3.20 \pm 0.57 ~ { } km ^ { -1 } between 10 and 30 kHz , considerably larger than previous theoretical estimates .
Expressed as an attenuation length , the analyses give a consistent result for \lambda \equiv 1 / \alpha of \sim 300 m with 20 % uncertainty .
No significant depth or frequency dependence has been found .