Forward masking of dynamic acoustic intensity : effects of intensity region and end-level

Overestimation of loudness change typically occurs in response to up-ramp auditory stimuli (increasing intensity) relative to down-ramps (decreasing intensity) matched on frequency, duration, and end-level. In the experiment reported, forward masking is used to investigate a sensory component of up-ramp overestimation: persistence of excitation after stimulus presentation. White-noise and synthetic vowel 3.6 s up-ramp and down-ramp maskers were presented over two regions of intensity change (40–60 dB SPL, 60–80 dB SPL). Three participants detected 10 ms 1.5 kHz pure tone signals presented at masker-offset to signal-offset delays of 10, 20, 30, 50, 90, 170 ms. Masking magnitude was significantly greater in response to up-ramps compared with down-ramps for masker–signal delays up to and including 50 ms. When controlling for an end-level recency bias (40–60 dB SPL up-ramp vs 80–60 dB SPL down-ramp), the difference in masking magnitude between up-ramps and down-ramps was not significant at each masker–signal delay. Greater sensory persistence in response to up-ramps is argued to have minimal effect on perceptual overestimation of loudness change when response biases are controlled. An explanation based on sensory adaptation is discussed.