Title page for ETD etd-10022007-145242
|Type of Document
||Haas, Ellen Carla
||The perceived urgency and detection time of multi-tone and frequency-modulated warning signals in broadband noise
||Industrial and Systems Engineering
|Casali, John G.
|Dryden, Robert D.
|Kemmerling, Paul T. Jr.
|Price, G. Richard
|Snyder, Harry L.
|Date of Defense
In some environments, there is a serious mismatch
between the perceived (psychoacoustic) urgency of a warning
and its situational urgency. In addition, many auditory
warnings are not detectable within their environments. This
research examined several prominent pulse parameters which
affect the perceived urgency and detection time of auditory
warning signals. These elements included pulse format
(multitone sequential, multitone simultaneous, and rising
sawtooth frequency-modulated pulse formats), pulse level (65
dBC and 79 dBC), and time between pulses (0 ms, 150 ms, and
300 ms). The environments of interest were those settings
with steady-state broadband machinery noise. Conditions
included a loading task which presented additional
attentional demands upon the subject during the signal
detection task. Free-modulus magnitude estimation
quantified the relationship between auditory signal
parameters and changes in perceived urgency. The method of
paired comparisons was used to compare the perceived urgency
of the auditory stimuli. Simple reaction time measured
signal detectability. Signal effects were analyzed using a
Results indicated that there was a small but
statistically significant relationship between perceived
urgency and detection time. As perceived urgency increased,
detection time decreased. Both perceived urgency and
detection time were influenced by pulse level and format.
The higher pulse level resulted in a greater perceived
urgency of the signal and shorter detection time.
Sequential signals were rated as less urgent than the other
pulse formats, and subjects took longer to detect their
occurrence. Under most conditions, there was no significant
difference in the perceived urgency or detection time of
simultaneous and frequency-modulated pulses. Time between
pulses (inter-pulse interval) affected only perceived
urgency, not detection time. The shorter the time between
pulses, the greater the perceived urgency of the signal.
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