Auditory Superiority (Tecumseh Fitch )

Subject: Auditory Superiority
From:    Tecumseh Fitch  <tec(at)DREW.COG.BROWN.EDU>
Date:    Wed, 23 Jun 1993 15:13:32 -0400

> We're looking for any kind of work on human perception to find > caracteristics of the auditory sytem that are better than the visual > system. I and my collaborator Greg Kramer recently reported on some work on just this topic; it will appear in the proceedings of the ICAD (International Conference on Auditory Display) conference which happened in Santa Fe in October '92. The proceedings volume is in press at Addison-Wesley; it should be out by September. In brief, we studied a complex task requiring simultaneous monitoring of many continuously-changing variables, and found an auditory display to be superior to a standard visual display. College undergrads were briefly trained as anesthesiologists: they learned to monitor 8 physiological variables in a computer-simulated human body, and to respond appropriately to medical emergencies like overdose, blood loss, etc. Information from the "digital patient" was presented through either a standard visual display (a strip chart) or an auditory display which we created. The auditory display used two "base streams" which sounded like a heart beating and a person breathing, respectively. These conveyed information (not surprisingly) on heart rate and breathing rate. Other, more abstract, variables were "piggy-backed" onto these base streams: for example, blood pressure controlled the pitch of the heart sound, and body temperature controlled the center frequency of the band-pass filter used to make the breathing sound. We found that subjects responded faster AND more accurately when using the auditory display than with the visual display. The results suggested that subjects formed an gestalt representation of each medical problem when using the auditory display, and were less able to do this with the visual display. These results may not surprise people working in audition: it seems intuitively obvious that we are able to process multiple information sources simultaneously in audition (why else would people enjoy chamber music and symphonies?). In contrast, the primate visual system is adapted for foveating individual objects serially. As intuitive as these results may be, they are apparently surprising to some (see the writeup of our study in this month's American Scientist, 81(3) p 229) Other examples (in simpler tasks) are Tzelgov et al. (1987: Human Factors 29(1): 87-95), who found auditory superiority in a Geiger counter task, and Lewandowski and Kobus (1989: Human Perf. 2(1): 73-84) who got faster (but less accurate) performance with audition in a simple sonar target ID task. > There is a recent human study [Perrott et al.,1993, JASA 93:2134-2138] > that shows that the auditory modality is as good, if not better than > the visual in determining the relative spatial directions of stimuli > presented sequentially. Perrott et al. found no significant difference between minimum audible angle (MAA) and minimum visible angle (MVA) under their experimental conditions, but it is important to realize that their MVAs were orders of magnitude higher than the generally-accepted best values for vision (less than 10 sec of arc, vs. their 27 minutes of arc!). Thus the result, while theoretically quite interesting, may have limited practical importance. Tecumseh Fitch (tec(at) Dept. of Cognitive and Linguistic Sciences Brown University, Box 1978 Providence, RI 02912

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Electrical Engineering Dept., Columbia University