A loudness model for time-varying sounds predicts asymmetries in estimates of loudness change for sounds that increase or decrease in level.

Previous research has demonstrated a robust asymmetry in loudness judgements for rising and falling level tone stimuli, showing greater loudness and loudness change for rising sounds. In the literature, this has been interpreted to reflect an adaptive perceptual bias, resulting from an evolutionary advantage that increases the margin of safety when reacting to an approaching sound-producing object. The current experiment tested whether a loudness model was able to predict asymmetries in loudness-change judgments for rising and falling sounds, providing an alternative explanation to the adaptive perceptual bias theory. Blindfolded participants were presented with 1-kHz tones that increased or decreased in level by 15 dB, with different ranges of presentation levels (60/75, 65/80, 70/85, 75/90 dB). They were asked to report how much each sound changed in loudness, either verbally or using a tactile slider. Participants reported greater loudness changes for rising than falling tones for both response modes, the asymmetry increasing with increasing overall level. The results were accurately predicted by a loudness model, suggesting that an adaptive perceptual bias is not necessary to explain asymmetry in loudness-change estimates for rising and falling level sounds.