Title page for ETD etd-08032004-141805

Type of Document

Master's Thesis

Author

Fitch, Gregory Malcolm John

Author's Email Address

gfitch@vt.edu

URN

etd-08032004-141805

Title

Drivers' Ability to Localize Auditory and Haptic Alarms in Terms of Speed and Accuracy

Degree

Master of Science

Department

Industrial and Systems Engineering

Advisory Committee

Advisor Name	Title
Kleiner, Brian M.	Committee Chair
Babski-Reeves, Kari L.	Committee Member
Kiefer, Raymond J.	Committee Member
Lee, Suzanne E.	Committee Member

Keywords

Sound Localization
Auditory Alarm
Spatial Audio Display
Haptic Display

Date of Defense

2004-06-29

Availability

unrestricted

Abstract

This study investigated automobile drivers' ability to localize auditory and haptic (touch)
alarms in terms of speed and accuracy. Thirty-two subjects, balanced across age (20-30 years
old and 60-70 years old) and gender, participated in the study. Subjects were screened for
minimum hearing of 40 dB for 500 Hz through 4000 Hz auditory tones, and maximum
bilateral hearing differences of 10 dB. The experiment consisted of subjects identifying the
target location of an alarm while driving a 2001 Buick LeSabre at 55 mph in light traffic.
Four alarm modes were tested: 1) an auditory broadband alarm, 2) a haptic seat, 3) a
combination of the haptic and the auditory alarm modes, and 4) a combination of the haptic
alarm mode with a non-directional auditory alarm played from the front speakers of the
vehicle. The alarms were evoked from eight target locations: the front-left, front, frontright,
right, back-right, back, back-left, and left. The target locations of the auditory alarm
mode existed around the interior of the car cabin using the vehicle's stock sound system
speakers. The haptic alarm target locations existed in the bottom of the driver seat using an
eight-by-eight grid of actuators. The experimenter evoked the alarms while subjects drove
along a two-lane highway, and the alarms were not associated with any actual collision threat.
Subjects were instructed to quickly identify the location of the alarm by calling them out,
while being as correct as possible. Their choice response time and target location selection
was recorded. The alarms were presented approximately every minute during fifteen-minute
intervals over the duration of two and a half hours. Subjects completed questionnaires
regarding their preference to the alarm modes. Under the conditions investigated, subjects
localized the haptic alarm mode faster and more accurately than the auditory alarm mode.
Subjects performed equally well with the haptic alarm mode and the two auditory and haptic
combination alarm modes in terms of speed and accuracy in identifying their location.
Subjects did express a preference for the addition of the auditory component to the haptic
alarm mode, perhaps owing to a heightened sense of urgency. However, subjects preferred
the haptic alarm mode on its own in response to hypothetical false alarm questions, perhaps
because it was less annoying. Alarm mode discriminability was believed to affect localization
accuracy and response time owing to its effect on the likelihood of correctly identifying a
target location and the attention resources required to differentiate adjacent target locations.

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