"Acceleration." . . "Human Factors Engineering & Man Machine System." . . "Human factors engineering." . . "Spectra." . . "Aircraft cabins." . . "Methodology." . . "Data acquisition." . . . . . . . "Interior Noise and Vibration Measurements on Operational Military Helicopters and Comparisons with Various Ride Quality Criteria"@en . . "This paper presents physical measurements of the interior noise and vibration obtained within eight operational military helicopters. The data were analyzed and are presented in the following forms: noise and vibration spectra, overall root-mean-square acceleration levels in three linear axes, peak accelerations at dominant blade passage frequencies, acceleration exceedance data, and overall and A-weighted sound pressure levels. Peak acceleration levels were compared to the ISO 1-hr reduced comfort boundary, the fatigue decreased proficiency boundary, and the NASA discomfort criteria. The A-weighted noise levels were compared to the NASA annoyance criteria, and the overall noise spectra were compared to MIL-STD-1294 (Acoustical Noise Limits in Helicopters) . It is shown that specific vibration components at blade passage frequencies for several aircraft exceeded both the ISO reduced comfort boundary and the NASA passenger discomfort criteria. The A -weighted noise levels, corrected for SPH-4 helmet attenuation characteristics, exceeded the NASA annoyance threshold for several aircraft. The spectral components of the noise at cruise, corrected for helmet attenuation, fell within the limits of MIL-STD-1294 for all aircraft."@en . . . . . . . "Interior noise and vibration measurements on operational military helicopters and comparisons with various ride quality criteria"@en . . "Interior noise and vibration measurements on operational military helicopters and comparisons with various ride qualitiy criteria" . . . . . . . . . . . . . . . . . . . . . . . . . "Mechanics." . . "Noise reduction." . . . . "Helicopters." . . "Acoustics." . . "Level(quantity)" . . "Measurement." . . "Vibration." . . "Cockpits." . . "Aircraft noise." . . "Comparison." . . "Military aircraft." . . "Peak values." . . "NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER." . .