Contributions of individual components to the overall loudness of a multitone complex.

The contributions of individual components to the overall loudness of a multitone complex were examined in a two-interval, loudness judgment task. Stimuli were five-tone complexes centered on 1000 Hz, with six different logarithmic frequency spacings, corresponding to bandwidths from 46 to 2119 Hz. Stimuli were presented for 300 ms (10 ms rise/fall). The overall level of the standard complex was fixed at 60 dB SPL (53 dB/component). Levels of the individual components of the comparison complex were selected at random from a rectangular distribution with a range of 20 dB. Perceptual weights were computed by calculating the point-biserial correlation between the difference in the level of each component across the two intervals and the subject's response. 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 more weight given to the lowest and highest frequency components. A relation between component weight and masked threshold was observed for all but the widest spacing condition. Perceptual weights and masked thresholds were largely in agreement with the loudness model [Moore et al., J. Audio. Eng. Soc. 45, 224-237 (1997)], except at the widest bandwidth.