ACOUSTICAL EVALUATION OF X-20A DYNA-SOAR FULL-PRESSURE SUIT ASSEMBLIES
AIR FORCE AEROSPACE MEDICAL RESEARCH LAB WRIGHT-PATTERSON AFB OH WRIGHT-PATTERSON AFB United States
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Data on the subjective Real-Ear Attenuation at Threshold REAT and noise transmission measurements at the helmet microphone and ear cup were obtained for two models of the suit assembly. The first models tested and evaluated were called the training models and were custom fitted for each of the Dyna-Soar pilots. During the test program, in which the pilots were acting as experimental subjects, the X-20A program was cancelled and only four of the six pilots completed the tests. The results of this evaluation revealed that various features of the assembly were unsatisfactory therefore, an improved version was fabricated to correct the undesirable deficiencies. From the acoustical standpoint, the assembly was redesigned to eliminate a resonance at 250 cps with the visor open. This improved second model was called the flight ready model. The report describes a comparative acoustical evaluation of the training models and flight-ready models of the suit assemblies. Evaluation consisted of 1 the subjective measurement of RealEar Attenuation at Threshold REAT and 2 the measurement of transmission loss through the helmet at the helmet microphone and ear cup position.