An effect of temporal asymmetry on loudness

A set of experiments was conducted to examine the loudness of sounds with temporally asymmetric amplitude envelopes. Envelopes were generated with fast-attack/slow-decay characteristics to produce F–S (or “fast–slow”) stimuli, while temporally reversed versions of these same envelopes produced corresponding S–F (“slow–fast”) stimuli. For sinusoidal (330–6000 Hz) and broadband noise carriers, S–F stimuli were louder than F–S stimuli of equal energy. The magnitude of this effect was sensitive to stimulus order, with the largest differences between F–S and S–F loudness occurring after exposure to a preceding F–S stimulus. These results are not compatible with automatic gain control, power-spectrum models of loudness, or predictions obtained using the auditory image model [Patterson et al., J. Acoust. Soc. Am. 98, 1890–1894 (1995)]. Rather, they are comparable to phenomena of perceptual constancy, and may be related to the parsing of auditory input into direct and reverberant sound.