Abstract:
This study examines the effect of dynamic changes in signal amplitude (temporal energy distribution) on loudness. Pure-tone (330-Hz) signals were gated with asymmetric temporal envelopes whose rise and fall times were unequal. These were presented either forward or reversed in time so that peak amplitudes appeared either early or late in the signals. Subjects judged late-peaking signals to be louder than early-peaking signals. The result is not in accord with an automatic gain control (AGC) model, which would predict that signals with a more rapid rise time would be less affected by AGC and thus appear louder. Alternative explanations to be discussed include (a) forward masking of the stimulus tail by the onset, and (b) a form of perceptual constancy whereby the slowly decaying stimulus tail is treated as reverberation and thereby not included in the judgment of loudness. [Work supported by NSF 9355034 and NIDCD 00087.]