Measuring Perceived Urgency to Create Safe Auditory Warnings

Abstract

Various pulse parameters, which were believed to affect the perceived urgency of multitone auditory warning signals, were investigated in a factorial experiment. The three independent variables included pulse fundamental frequency (200, 500, and 800 Hz), pulse sound pressure level above ambient (5, 25, and 40 dB sound pressure level [SPL]), and inter-pulse interval (0,250, and 500 ms). The psychophysical method of free-modulus magnitude estimation was used to measure subjective perceived urgency. Multivariate statistical analysis indicated that all independent variables and most variable interactions were significant. Perceived urgency increased as pulse level increased and inter-pulse interval decreased. Multidimensional scaling analysis indicated that signal level and inter-pulse interval were important in subject perception of signal similarity in terms of perceived urgency. Signals with high sound pressure levels and short inter-pulse intervals were perceived by subjects to have similar perceived urgency, as were signals with low sound pressure levels and long inter-pulse intervals.