Individual differences in loudness processing and loudness scales

Assessed parameters of the psychophysical function for loudness (a 1,000-Hz tone) for 9 undergraduates in 3 experiments: binaural loudness summation, temporal loudness summation, and judgments of loudness intervals. Findings reveal that the loudness scales that underlay the additive binaural summation closely approximated S. S. Stevens's (see record 1957-02311-001) sone scale but were nonlinearly related to the scales that underlay the subtractive interval judgments, the latter approximating W. R. Garner's (see record 1954-07051-001) lambda scale. Interindividual differences in temporal summation were unrelated to differences in scaling performance or in binaural summation. Although the exponents of magnitude-estimation functions and the exponents underlying interval judgments varied considerably from S to S, exponents computed on the basis of underlying binaural summation varied less. Results suggest that interindividual variation in the exponent of magnitude-estimation functions largely reflects differences in the ways that Ss use numbers to describe loudness and that the sensory representations of loudness are fairly uniform among people with normal hearing. The magnitude of individual variation in temporal summation seems at least as great as the magnitude of the variation in the underlying loudness scale. (78 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved).