Ellen C. Haas
Human Research and Engineering Directorate, U.S. Army Research Lab., Bldg. 520, Aberdeen Proving Ground, MD 21005
Judy Edworthy
Univ. of Plymouth, Plymouth, United Kingdom
In some environments, there is a serious mismatch between the perceived (psychoacoustic) urgency of a warning and its situational urgency (the urgency associated with the situation or condition that the signal represents). Several parameters which were believed to affect the perceived urgency of multitone auditory warning signals were investigated in a factorial experiment. These parameters were fundamental frequency (200, 500, and 800 Hz), time between signals (0, 300, and 500 ms), and signal level (5, 25, and 40 dB Lin SPL above the ambient noise level of a sound-treated chamber). The stimuli were 27 auditory signals, each signal consisting of a train of four repetitions. Free-modulus magnitude estimation quantified the relationship between auditory signal parameters and changes in perceived urgency. The effect of the three variables on perceived urgency will be discussed. The results of this experiment will be used in the development of a mathematical model in which the relationship between signal parameters and perceived urgency can be defined.