The following article will be published very soon in the Journal of Experimental Biology: Polar bear Ursus maritimus hearing measured with auditory evoked potentials Paul E. Nachtigall1, Alexander Ya. Supin 2, Mats Amundin3, Bengt Röken3 Thorsten Møller 3, T, Aran Mooney1,Kristen A. Taylor1, and Michelle Yuen1,4, 1Marine Mammal research Program, Hawaii Institute of Marine Biology, University of Hawaii.,HI, USA 2Institute of Ecology and Evolution of the Russian Academy of Sciences, Moscow, Russia, 3 Kolmården Djurpark, Kolmården, Sweden, 4National Marine Fisheries Service, Pacific Islands Regional Office, Honolulu, Hawaii. Summary While there has been recent concern about the effects of sound on marine mammals, including polar bears, there are no data available measuring the hearing of any bear. The in-air hearing of three polar bears was measured using evoked auditory potentials obtained while tone pips were played to three individually anaesthetized bears at the Kolmården Djurpark. Hearing was tested in ½ octave steps from 1 to 22.5 kHz. Measurements were not obtainable at 1 kHz and best sensitivity was found in the range from 11.2-22.5 kHz. Considering the tone pips were short and background noise measurements were available, absolute measurements were estimated based on an assumed mammalian integration time of 300 ms. These data show sensitive hearing in the polar bear over a wide frequency range and should cause those concerned with the introduction of anthropogenic noise into the polar bears environment to operate with caution. Paul E. Nachtigall Marine Mammal Research Program Hawaii Institute of Marine Biology 808 247-5297