Measurements of the noise attenuation provided by five flight helmets were obtained on a manikin head and compared with attenuation measurements obtained on human subjects according to the USASI Standard for Evaluating Real-Ear Attenuation at Threshold. The two sets of measurements were similar. The manikin method has certain advantages which should be considered in terms of the particular requirements of an evaluation program: (1) a helmet can be optimally fitted with little expenditure of time; (2) variability introduced by human factors is kept at a minimum; (3) high levels of noise can be used as the test stimulus; (4) visual and auditory monitoring of the attenuated noise provides the experimenter with a precise appraisal of the fit as adjustments are made; (5) manikin measurements are particularly useful in revealing improvements in attenuation resulting from minor modifications. (Author).