Use of perceptual weights to test a model of loudness summation

Abstract

We recently examined the contribution of individual components of a multitone complex to judgments of overall loudness by computing the perceptual weight listeners assign to each component in a loudness-matching task [Leibold et al., J. Acoust. Soc. Am. 117, 2597 (2005)]. Stimuli were five-tone complexes centered on 1000 Hz, with six different logarithmic frequency spacings, ranging from 1.012 to 1.586. When all components fell within the same critical band, weights varied little across components. In contrast, the range of weights increased with increasing frequency separation, with greater weight given to the lowest and highest frequency components. Perceptual weights were largely in agreement with the Moore et al. loudness model [J. Audio Eng. Soc. 45, 224–237 (1997)], except at the widest bandwidth. In the current study we further examined predictions of the loudness model, focusing on the widest frequency-spacing condition. Masked thresholds and jnds for intensity discrimination were measured for each component and were compared to weights. The model predicts more interaction in the widely spaced conditions than simple critical band models, but underestimates the true interactions in conditions where components are widely spaced. Central factors appear to influence loudness, masked thresholds, and intensity discrimination in these conditions. [Work supported by NIH/NIDCD.]