In the presence auditory detection of a sinusoidal signal in the presence of random noise, it has previously been demonstrated that the presence of a “pedestal” or background sinusoidal of the same frequency and phase as the signal increases detectability. This increase was confirmed in a two interval forced choice experiment in which a 1000-cps sinusoid was present in our of two 0.1-sec intervals, and the noise plus pedestal were present in both intervals. Pedestals of moderate intensity in phase with the signal increased detectability. Pedestals 90° out of phase with the signal did not improve detectability. Very large pedestals decreased detectability regardless of phase. A simple energy detection model was developed and its performance compared with the experimental results. The model consists of a bandpass filter, a rectifier or square-law element, and an integrator. The probability of correct detection varies with signal in a manner similar to the auditory results. Detectability is improved by an inphase pedestal and approaches that of a correlation detector in the limit of infinite pedestal. Detectability is not improved by 90° out-of-phase pedestals. However, the model does not predict decreasing detectability with large pedestals.

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