The -weighted attenuation estimated from the REAT for each method, protector, and laboratory. In each set of paired results, Method A attenuations are displayed on the left and Method B on the right. Each box plot gives the median, 25th and 75th percentiles; the error bars indicate the 10th and 90th percentiles; individual point represent the attenuations observed on individual trials for subjects outside the 10th and 90th percentiles.
The within-subject, between-subject, and between-laboratory standard deviations for the -weighted attenuations of each protector using Methods A and B.
The power estimates for the number of subjects necessary to achieve a resolution for the -weighted attenuations of each protector Methods A and B.
Subject recruitment and retention by laboratory. Participating laboratories were AFRL, , HLI, LARI, NIOSH, and USAARL
Mean hearing threshold levels and standard deviations (dB HL) for right and left ears.
Means and standard deviations of ear canal size (diameters), bitragion width, and head height.
Means and standard deviations of headband clamping force measured in Newtons. ( is the number of hearing protectors.)
Method-A mean attenuations and standard deviations in dB at each test frequency, by laboratory and protector.
Method-B mean attenuations and standard deviations in dB at each test frequency, by laboratory and protector.
-weighted attenuations in dB for Methods A and B, attenuation differences , standard error, student’s test, probability associated with , and lower and upper 95% confidence interval boundaries, across all laboratories and by individual laboratory for each protector.
Within-subject standard deviations in dB for Methods A and B for each protector.
Between-subject standard deviations in dB for Methods A and B for each protector.
Between-laboratory standard deviations in dB for Methods A and B for each protector.
Calculated numbers of subjects necessary to achieve resolution in the -weighted attenuation from between-subject and between-laboratory variances, for Methods A and B. (Results are shown with one decimal place for illustrative purposes.)
Comparison of advantages and disadvantages between Methods A and B.
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