Human Factors Evaluation of Vocoders for Air Traffic Control ... - FAA

Mean Intelligibility Rating
Radio Equipm ent Condition
8
7
6
5
4
3
2
1
JET PROP HELO NONE
Background Noise Condition
MA LE
FEMA LE
Figure 13. Mean intelligibility ratings as a function of sex of speaker and background noise for
analog radio messages.
Table 22 depicts the simple main effect of sex of speaker on the acceptability rating dependent
measure. An important characteristic of the simple main effect of sex on the acceptability rating
is that the significant effects occur with the same combinations of equipment and background as
the intelligibility rating analysis. Moreover, these effects occur with identical ordering in the
means as the intelligibility rating. This is exhibited in the results for the acceptability rating in
Table 23.
Table 22. Analysis of Simple Main Effects for Speaker Acceptability Ratings
Equipment Background F Statistic Result
Vocoder A Jet 2.24 Not Significant
Vocoder A Propeller 0.51 Not Significant
Vocoder A Helicopter 24.94 Significant*
Vocoder A None 79.90 Significant*
Vocoder B Jet 8.83 Significant*
Vocoder B Propeller 0.45 Not Significant
Vocoder B Helicopter 38.44 Significant*
Vocoder B None 26.05 Significant*
* p < .05
Radio Jet 0.36 Not Significant
Radio Propeller 0.00 Not Significant
Radio Helicopter 12.12 Significant*
Radio None 5.39 Significant*
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