Auditory Information Systems in Military Aircraft: Current Configurations Versus the State of the Art.

Abstract : The complete ensembles of auditory signals in selected USAF aircraft (the F-4D, F-15, two models of the F-16, the C-5, and the C-141) are described and evaluated. Human factors research related to the design of speech and non-speech and non-speech auditory signals is reviewed and the fundamentals of speech synthesis technology are described. Major findings are: that auditory signals are not well standardized among the aircraft, even between those with similar combat roles that a relatively large number of non-speech auditory signals are used, which may make it difficult for the aircrew to recall the meanings of all the signals; that some non-speech signals are sufficiently similar that they may be confused, particularly in high workload and stressful conditions; and that the criticality of the warnings is not reliably indicated by any characteristic of the signals. Five problem areas requiring further research are discussed: reduction of signal loudness, annoyance, and disruption of other functions; enhancement of the distinctiveness and masking resistance of non-speech signals; effects of concurrent warning signals on aircrew performance in critical operational contexts; additional uses of auditory information in order to relieve visual workload; the need for guidelines for deciding which information should be provided aurally, which should be speech versus non-speech, and for designing speech messages; and optimization of synthesized speech for cockpit applications, including its attention-getting capability, distinctiveness, intelligibility, and ease of comprehension. (Author)