LONG-TERM GOALS

Broaden the baseline of hearing measures of marine mammals by increasing the number of animals and species measured. The effects of sound on wild populations of animals can best be determined if baseline hearing measures are known. Develop an understanding of the basic processes of odontocete echolocation. Echolocation is the principal sense for odontocete foraging and its understanding is therefore crucial for estimating the effects of sound on foraging and populations. Examine the control of hearing during echolocation. Improve the measurement of marine mammal hearing by developing and refining hearing procedures particularly those that will rapidly measure the hearing of stranded and temporarily caught animals. Comparatively examine the basic hearing mechanisms of marine mammal species. Develop and refine the measurement of hearing during echolocation particularly the hearing of the outgoing signals and the echoes from nearby and distant targets. Examine automatic gain control mechanisms in odontocete echolocation. Develop an understanding of the basic processes used by odontocetes to actively discriminate fine differences in echolocation targets and to model those processes for use in the development of improved sonars. 1 DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited