Detection of simple and complex tones in fixed and random conditions

Abstract

Psychometric functions for detection of pure (220, 1100, or 3850 Hz) and complex tones in the presence of a 64 dB SPL uniformly masking noise were measured in a 21, 2AFC paradigm. The complex tone consisted of 18 equally intense components spaced about one critical band apart between 110 and 7260 Hz. In experiment 1, all levels for a single signal were presented in mixed order within a block of trials. Results for eight normal listeners show parallel psychometric functions for simple and complex tones. Thresholds are 43–44 dB SPL for the pure tones and about 37 dB SPL per tone for the complex tone. In experiment 2, all levels and signals were presented in random order within each block of trials. Results for four normal listeners show psychometric functions parallel to those in experiment 1. Thresholds are about 46 dB for the pure tones and 40.5 dB for the complex tone. These results are consistent with a multiband energy‐detector model in which the decision is based on an unweighted sum of decision variables across an optimum selection of channels. [Supported by Deutsche Forschungsgemeinschaft and NIH‐NINCDS R0 1NS 18280.]