Ambient noise measured in the deep ocean is studied in the context of asearch for signals from ultra-high energy cosmic ray neutrinos. The spectralshape of the noise at the relevant high frequencies is found to be very stablefor an extensive data set collected over several months from 49 hydrophonesmounted near the bottom of the ocean at ~1600 m depth. The slopes of theambient noise spectra above 15 kHz are found to roll-off faster than the -6dB/octave seen in Knudsen spectra. A model attributing the source to an uniformdistribution of surface noise that includes frequency-dependent absorption atlarge depth is found to fit the data well up to 25 kHz. This depth dependentmodel should therefore be used in analysis methods of acoustic neutrino pulsedetection that require the expected noise spectra.
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