Crossmodal sound design for rotary switches: Toward congruent audio-tactile heaviness

Abstract

This study explores the perceptual integration of tactile and auditory feedback in rotary switch operations, introducing the concept of audio-tactile heaviness congruency. Through a two-stage experimental approach, we first identify acoustic features—specifically, lower frequencies and triangular waveforms—that enhance the perception of heaviness and comfort in unimodal auditory stimuli. Subsequently, we show that the alignment of perceived heaviness between tactile click torque and auditory frequency significantly predicts perceived audio–tactile congruency (i.e., the sense of a well‑matched tactile–auditory combination) in multimodal conditions. To quantify this relationship, we propose a novel index, Diff_Heaviness, representing the difference in unimodal heaviness perception, which shows a strong correlation with perceived congruency (r = 0.70). Furthermore, a predictive model is developed to estimate audio-tactile congruency based on physical parameters, offering practical guidance for optimizing multimodal interface design. These findings highlight the importance of crossmodal alignment in enhancing user experience and provide a quantitative framework for the design of rotary switches and similar interactive devices.