Characterizing Perception of Impulse Sounds Through Subjective Ratings and Pupillometric Responses.

Impulse sounds such as clinking dishes or slamming objects are often perceived as particularly intense or uncomfortable, yet their perceptual characterization remains insufficiently understood. The present study systematically examined subjective and physiological responses to ecologically valid impulse sounds in young normal-hearing adults. Twenty-seven participants rated nine impulse sounds presented at peak levels between 80 and 120 dB SPL in three acoustic conditions: anechoic, reverberant (room-convolved), and anechoic embedded in the International Speech Test Signal (ISTS) at 65 dB SPL. Loudness and discomfort were assessed using categorical rating scales, and pupil dilation was recorded as an index of autonomic arousal. Both perceptual scales followed Stevens-type growth functions. Loudness increased gradually with level, whereas discomfort showed a delayed onset, but steeper growth once activated. Test-retest reliability was excellent for both scales (ICC ≈0.88). Acoustic condition significantly influenced perception: reverberant stimuli yielded higher perceived intensity and lower 50% thresholds than anechoic presentations for most impulse types, while embedding impulses in speech produced comparatively small effects. Mean pupil dilation increased with presentation level and was significantly associated with both loudness and discomfort ratings. Linear mixed-effects modeling demonstrated that subjective ratings explained pupil dilation more strongly than physical level once both were included in the model. Neither uncomfortable loudness levels nor self-reported sound sensitivity significantly predicted ratings or physiological responses. These findings provide a systematic characterization of impulse sound perception in a normal-hearing population and demonstrate a close correspondence between subjective intensity judgments and autonomic responses under controlled laboratory conditions.