Auditory icons caricatures of everyday sounds have the potential
to convey information by non-verbal means quickly and accurately.
Two experiments investigated the application of auditory icons as
warning signals to the civil aviation cockpit environment. Warning
signals that are iconic and that stand in a direct relation to the
event being signalled, such as the sound of coughing to signal the
presence of carbon monoxide, should convey information about the
nature of the critical event as well as alerting the operator that
there is a problem. By contrast, signals that are arbitrarily
associated with an event, such as a beep to signal the presence of
carbon monoxide, provide little information about the nature of the
event. Speed and accuracy of recognition in response to these
different types of warnings may also be influenced by modality
(visual, auditory, auditory + visual) and by task demand (low,
high). Experiment 1 investigated effects of signal iconicity
(iconic, abstract), modality, and task demand on warning
recognition speed and accuracy. One-hundred and seventy-eight
participants completed a computer-based training session and test
task that involved responding to warnings associated with nine
critical events while completing low- and high-demand concurrent
tasks. As hypothesized, fewer training trials were required to
learn iconic warnings compared with abstract warnings. During the
test phase, the effect of iconicity, as hypothesized, was
influenced by modality and task demand. Bimodal (auditory + visual)
warnings were recognized with the greatest consistency and
accuracy. Auditory abstract warnings elicited slow reaction times
and poor accuracy. Auditory iconic warnings, under conditions of
high demand, evoked levels of accuracy comparable with bimodal
warnings. Experiment 2 investigated recognition speed and accuracy
in response to four auditory iconic and four abstract warnings in
an Advanced Aviation Training Device. As hypothesized, accuracy was
greater in response to auditory iconic than abstract warnings and
recognition accuracy and reaction time were unaffected by level of
flying experience. Reaction times in the Advanced Aviation Training
Device were approximately 1 second. These initial experiments
suggest that there is potential for the use of auditory iconic
warnings and bimodal warnings as the means, not only to alert, but
also inform pilots about the nature of a critical incident.