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  • 1
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    Development of noise and vibration ride comfort criteria (1979)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: A laboratory investigation was directed at the development of criteria for the prediction of ride quality in a noise-vibration environment. The stimuli for the study consisted of octave bands of noise centered at 500 and 2000 Hz and vertical floor vibrations composed of either 5 Hz sinusoidal vibrations, or random vibrations centered at 5 Hz and with a 5 Hz bandwidth. Results indicated that the total subjective discomfort response could be divided into two subjective components. One component consisted of subjective discomfort to vibration and was found to be a linear function of vibration acceleration level. The other component consisted of discomfort due to noise which varied logarithmically with noise level (power relationship). A model of subjective discomfort that accounted for the interdependence of noise and vibration was developed. The model was then used to develop a set of criteria (constant discomfort) curves that illustrate the basic design tradeoffs available between noise and vibration.
    Keywords: AIR TRANSPORTATION AND SAFETY
    Type: Acoustical Society of America; vol. 65
    Format: text
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  • 2
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    Evaluation of ride quality measurement procedures by subjective experiments using simulators (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Since ride quality is, by definition, a matter of passenger response, there is need for a qualification procedure (QP) for establishing the degree to which any particular ride quality measurement procedure (RQMP) does correlate with passenger responses. Once established, such a QP will provide very useful guidance for optimal adjustment of the various parameters which any given RQMP contains. A QP is proposed based on use of a ride motion simulator and on test subject responses to recordings of actual vehicle motions. Test subject responses are used to determine simulator gain settings for the individual recordings such as to make all of the simulated rides equally uncomfortable to the test subjects. Simulator platform accelerations vs. time are recorded with each ride at its equal discomfort gain setting. The equal discomfort platform acceleration recordings are then digitzed.
    Keywords: BEHAVIORAL SCIENCES
    Type: The 1975 Ride Quality Symp.; p 217-265
    Format: application/pdf
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  • 3
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    Effect of noise spectra and a listening task upon passenger annoyance in a helicopter interior noise environment (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The effects of helicopter interior noise on passenger annoyance were studied. Both reverie and listening situations were studied as well as the relative effectiveness of several descriptors (i.e., overall sound pressure level, A-weighted sound pressure level, and speech interference level) for quantifying annoyance response for these situations. The noise stimuli were based upon recordings of the interior noise of a civil helicopter research aircraft. These noises were presented at levels ranging from approximately 68 to 86 dB(A) with various gear clash tones selectively attenuated to give a range of spectra. Results indicated that annoyance during a listening condition is generally higher than annoyance during a reverie condition for corresponding interior noise environments. Attenuation of the planetary gear clash tone results in increases in listening performance but has negligible effect upon annoyance for a given noise level. The noise descriptor most effective for estimating annoyance response under conditions of reverie and listening situations is shown to be the A-weighted sound pressure level.
    Keywords: BEHAVIORAL SCIENCES
    Type: NASA-TP-1590 , L-13233
    Format: application/pdf
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  • 4
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    Effect of vibration duration on human discomfort (1978)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The duration effects of random vertical vibration on passenger discomfort were studied in a simulated section of an aircraft cabin configured to seat six persons in tourist-class style. Variables of the study included time of exposure (0.25 min to 60 min) and the rms amplitude of vibration (0.025g to 0.100g). The vibrations had a white noise spectrum with a bandwidth of 10 Hz centered at 5 Hz. Data indicate that the discomfort threshold occurred at an rms vertical acceleration level of 0.027g for all durations of vibration. However, for acceleration levels that exceeded the discomfort threshold, a systematic decrease in discomfort occurred as a function of increasing duration of vibration. For the range of accelerations used, the magnitude of the discomfort decrement was shown to be independent of acceleration level. The results suggest that discomfort from vertical vibration applied in the frequency range at which humans are most sensitive decreases with longer exposure, which is the opposite of the recommendation of the International Standard ISO 2631-1974 (E) Guide for the Evaluation of Human Exposure to Whole-Body Vibration.
    Keywords: BEHAVIORAL SCIENCES
    Type: NASA-TP-1283 , L-12248
    Format: application/pdf
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  • 5
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    Experimental determination of the rattle of simple models (1978)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The effect of the excitation frequency on the rattle boundaries of simple models was investigated. The frequency range investigated was from 40 to 4,000 Hz. A 1-inch steel ball was studied to determine the rattle boundary for both vertical motion and for the ball suspended as a pendulum. Effects of surface contact and weight were also studied. Results indicate that the shape of the rattle boundary depends on the particular configuration being investigated as well as the range of frequency being investigated. Although there was condiderable scatter in the data, the general trend indicates that the level of acceleration required for the onset of rattle was independent of excitation frequency.
    Keywords: ENGINEERING (GENERAL)
    Type: NASA-TM-78756
    Format: application/pdf
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  • 6
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    Subjective response to combined noise and vibration during flight of a large twin-jet airplane (1976)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A NASA twin-jet airplane was used to obtain controlled noise and vibration environments during flight while obtaining subjective responses from 13 passenger-subjects (6 females and 7 males). Subjective ratings of overall comfort, comfort when considering only vibration, and comfort when considering only noise were obtained during times of different vibration and noise environments. Passenger-subjects were able to distinguish and rate noise better than vibration. In addition, there was a statistically significant difference in ratings of ride comfort due to both sex type and flight experience. Males rated flying discomfort much more severely than females when rating the overall ride and the ride when considering only the noise environment. Experienced passengers also rated the overall ride to be more uncomfortable than inexperienced passengers.
    Keywords: BEHAVIORAL SCIENCES
    Type: NASA-TM-X-3406 , L-10578
    Format: application/pdf
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  • 7
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    Ride quality criteria of multifactor environments (1978)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The paper describes a comprehensive ride quality model that accounts for the effects of multifrequency and multitaxis vibration inputs as well as the interactive effects of noise and vibration upon passenger discomfort. The model is based on extensive experimental studies involving a realistic multi-degree-of-freedom laboratory simulator, and data relating to human discomfort response to vertical, lateral, and roll vibrations are presented. Results of studies involving vibration stimuli are expressed by sets of equal discomfort curves for each of three axes of vibration. A set of noise-vibration curves are obtained by an additive procedure, shown to be valid in the range under consideration, which combines the discomfort components due to noise and vibration. Other results from the study of human response to combined noise and vibration stimuli are reported.
    Keywords: MAN/SYSTEM TECHNOLOGY AND LIFE SUPPORT
    Type: Annual Meeting; Jan 16, 1978 - Jan 30, 1978; Washington, DC
    Format: text
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  • 8
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    Noise and vibration ride comfort criteria (1976)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Two of the most important factors, namely, vibration and noise, were studied to (1) determine whether composite or separate noise and vibration criteria are needed for the prediction of ride quality, (2) determine a noise correction for the previously-defined vibration criteria of the ride quality model, (3) assess whether these noise corrections depend on the nature of the vibration stimuli, i.e., deterministic as opposed to random, and (4) specify noise-vibration criteria for this combined environment. The stimuli for the study consisted of octave bands of noise centered at 500 or 2,000 Hz and vertical vibrations composed of either 5 Hz sinusoidal vibration or random vibrations centered at 5 Hz and with a 5 Hz bandwidth. The noise stimuli were presented at levels ranging from ambient to 95 dB(A) and the vibrations at levels ranging from 0.02 to 0.13g rms.
    Keywords: BEHAVIORAL SCIENCES
    Type: NASA-TM-X-73975 , Acoustical Soc. of Am. Meeting; Nov 16, 1976 - Nov 19, 1976; San Diego, CA; United States
    Format: application/pdf
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  • 9
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    A study of helicopter interior noise reduction (1975)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The interior noise levels of existing helicopters are discussed along with an ongoing experimental program directed towards reducing these levels. Results of several noise and vibration measurements on Langley Research Center's Civil Helicopter Research Aircraft are presented, including measurements taken before and after installation of an acoustically-treated cabin. The predominant noise source in this helicopter is the first stage planetary gear-clash in the main gear box, both before and after installation of the acoustically treated cabin. Noise reductions of up to 20 db in some octave bands may be required in order to obtain interior noise levels comparable to commercial jet transports.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA-TM-X-72655 , L-10076 , Ann. Natl. Forum of the Amer. Helicopter Soc; May 01, 1975
    Format: application/pdf
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  • 10
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    Noise and vibration ride comfort criteria (1976)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A program is underway at Langley Research Center to develop a comprehensive ride quality model based upon the various physical and psychological factors that most affect passenger ride comfort. Two of the most important factors, namely, vibration and noise were studied to (1) determine whether composite or separate noise and vibration criteria are needed for the prediction of ride quality, (2) determine a noise correction for the previously-defined vibration criteria of the ride quality model, (3) assess whether these noise corrections depend on the nature of the vibration stimuli, i.e., deterministic as opposed to random, and (4) specify noise-vibration criteria for this combined environment. The stimuli for the study consisted of octave bands of noise centered at 500 or 2000 Hz and vertical vibrations composed of either 5 Hz sinusoidal vibration or random vibrations centered at 5 Hz and with a 5 Hz bandwidth. The noise stimuli were presented at levels ranging from ambient to 95 dB(A) and the vibrations at levels ranging from 0.02 to 0.13 g-rms.
    Keywords: MAN/SYSTEM TECHNOLOGY AND LIFE SUPPORT
    Type: Meeting of the Acoustical Society of America; Nov 16, 1976 - Nov 19, 1976; San Diego, CA
    Format: text
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