An expert panel reviewed the expanding literature on marine mammal (cetacean and pinniped) auditory and behavioral responses to sound exposure to develop comprehensive, scientifically based noise exposure criteria [Aquatic Mammals 33(4)]. They used precautionary extrapolation procedures to predict exposure levels above which adverse effects (both physical and behavioral) could be expected. Due to the paucity of data on long-term exposures, criteria were developed for single exposure events only. Marine mammals were broken into functional hearing groups. Exposure types were lumped into three broad classes (single pulses, multiple pulses, and nonpulses). Levels estimated to induce permanent noise-induced hearing loss were determined for each of 15 sound type/animal group combinations. For example, injury criteria for pinnipeds in water exposed to multiple pulses were 186 dB re 1 μPa2 -s (weighted SEL) and 218 dBpk re 1 μPa (unweighted peak SPL). Discrete behavioral disturbance thresholds could only be determined for exposure to single pulses. For other exposures, available data on behavioral responses were ranked by severity and significance. This severity scaling and the resulting conclusions will be described. New research required to improve criteria and to assess cumulative and ecosystem-level effects will also be considered, along with current policy and/or regulatory applications.

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A6struct-The structure and performance of a class of nonlinear detectors for discrete-time signals in additive white noise are investigated. The detectors considered consist of a zero-memory nonlinearity (ZNL) followed by a linear filter whose output is compared with a threshold. That this class of detectors is a reasonable one to study is apparent from the fact that both the Neyman-Pearson optimum and the locally optimum (i.e., weak-signal optimum) detectors for statistically independent noise samples can be put into this form.The measure of detector performance used is the asymptotic relative efficiency (ARE) of the nonlinear detector under study with respect to a linear detector appropriate for the same detection problem. A general expression for this ARE is given along with the result that the nonlinearity maximizing this expression is any linear function of the nonlinearity in the appropriate constant-signal locally optimum detector.To illustrate the structure and performance of these nonlinear detectors for a wide range of non-Gaussian noise distributions, three general classes of symmetric, unimodal, univariate probability density functions are introduced that are generalizations of the Gaussian, Cauchy, and beta distributions.

Three studies were conducted to examine the relationship between a multi-dimensional measure of locus of control and sociopolitical activism, controlling for the effects of political ideology. In Study 1, 98 male college students completed a measure of conservatism-liberalism. Kerpelman's Activism scale, and locus of control scales designed to differentiate between two types of externals: belief in powerful others versus belief in chance forces. In Studies 2 and 3, female college students (Ns=26 and 40) who differed in the extent of their participation in leftist political activities or feminist causes responded to the multidimensional locus of control scales. As predicted, results from analyses of variance and trend analyses indicate that for liberals, increases in expectancies of control by powerful others are positively associated with increases in activism, while for conservatives, there is a negative relationship. The importance of controlling for ideology and the implications of the differentiated view of externality for understanding social action are discussed.