Engineering topics

Lukas, J. S.

Publications and source records attributed to Lukas, J. S..

15 records

NASA NTRS1975

Noise and sleep - A literature review and a proposed criterion for assessing effect

Results of a number of studies on the effects of various types of noise on the sleep of subjects of both sexes and a wide range of age groups are reviewed to develop a tentative criterion for assessing these effects. Available data suggest that reasonably accurate predictions of sleep disruption may be made if the interfering noise is specified in units (EPNdB or EdBA) which account for its spectral characteristics and duration. When EPNdB units are used as the measure of noise intensity, the correlation coefficient between intensity and the probability of no sleep disturbance is -0.86. Because of the paucity of data on the long-term results of frequent behavioral wakings or arousals, it is suggested that disturbance of sleep be defined as an electroencephalographic change of one or more sleep stages.

Lukas, J. S.↗

NASA NTRS1975

Effects on sleep of noise from two proposed STOL aircraft

Responses, both overt behavior and those measured by electroencephalograph, to noise by eight male subjects were studied for sixteen consecutive nights. Test stimuli were: (1) The simulated sideline noise of a short takeoff and landing aircraft with blown flaps; (2) the simulated sideline noise of a STOL aircraft of turbofan design; (3) the simulated takeoff noise of the blown flap STOL aircraft; and (4) a four second burst of simulated pink noise. Responses to each noise were tested at three noise intensities selected to represent levels expected indoors from operational aircraft. The results indicate that the blown flap STOL aircraft noise resulted in 8 to 10 percent fewer sleep disturbance responses than did the turbofan STOL aircraft when noises of comparable intensities from similar maneuvers were used.

Lukas, J. S.↗

NASA NTRS1974

Reliability of laboratory tests of VSTOL and other long duration noises

Paired-comparison and magnitude estimations of the subjective noisiness or unacceptability of noise from fixed wing jet aircraft and simulated noise of VSTOL aircraft were obtained from groups of subjects given different instructions. These results suggest that VSTOL noises can be evaluated in terms of their noisiness or unwantedness to people with reasonable accuracy by units of the physical measures designated as PNdBM, with or without tone corrections, and dBD sub 2. Also, that consideration should be given to the use of D sub 2 as an overall frequency weighting function for sound level meters instead of the presently available A weighting. Two new units of noise measurement, PLdB and dB(E), used for predicting subjective noisiness, were found to be less accurate than PNdBM or dBD sub 2 in this regard.

Kryter, K. D.↗

NASA NTRS1973

Arousal from sleep by noises from aircraft with and without acoustically treated nacelles

The electroencephalographic and behavioral responses during sleep of four subjects, aged 46 to 58 years, to three types of noises were tested over 14 consecutive nights. The stimuli were two DC-8 jet landing noises (each 30 seconds in duration and coming from DC-8 aircraft with and without acoustical treatment on the engine nacelles) and a 4-second burst of pink noise. Each of the noises was tested at nominal intensities of 61 and 79 dBA. Other physical descriptors of the noises were measured or computed. The results indicate that for an equivalent degree of sleep disruption, noise form the jet aircraft with untreated nacelles must be about 6 dBA less intense than the jet with acoustically treated nacelles. Predictions of the effects of noise on sleep appear, tentatively, to attain the highest accuracy when the physical descriptor of noise intensity includes information about the impulsive characteristics of that noise as well as its long-term spectral content.

Lukas, J. S.↗

NASA NTRS1972

Simulated indoor sonic booms judged relative to noise from subsonic aircraft

Judgment tests were conducted in which subjects equated the subjective unwantedness or noisiness of simulated indoor sonic booms with the flyover noise of a subsonic jet aircraft as heard indoors. It was found that the spectral content of the booms, as affected by changes in the rise time of the booms, influenced the relative subjective noisiness of the booms in a way predictable from certain physical measures of Max and EPNL. However, a correction factor is required for predicting from physical measures the subjective noisiness of sonic booms when compared to nonimpulsive subsonic aircraft flyover noise measured in the same physical units. It appears that a somewhat different correction value is required for booms heard outdoors than when heard indoors.

Kryter, K. D.↗

NASA NTRS1972

Effects of aircraft noises on the sleep of women

The electroencephalographic and behavioral responses during sleep of eight women subjects, aged 29 to 49 years, to subsonic jet flyover noise and simulated sonic booms were tested over 14 consecutive nights. Stimulus intensities were 101, 113, and 119 PNdB (as if measured out-of-doors) for the subsonic jet flyover and 0.67, 2.50, and 5.0 psf (as if measured out-of-doors) for the simulated sonic booms. It was found that the women were awakened, on the average, by approximately 42 percent of the flyover noises and by approximately 15 percent of the simulated sonic booms. Comparison of the results of this study with those of a similar study using men as subjects revealed that women were awakened more frequently by the subsonic jet flyover noise then were the men, while men were awakened more frequently by the simulated sonic boom.

Lukas, J. S.↗

NASA NTRS1972

Effects of aircraft noise on human sleep.

Under controlled conditions in two test rooms, studies were made of the response of sleeping subjects to the stimuli of simulated sonic booms and subsonic jet aircraft noise. Children were relatively nonresponsive to the stimuli. In general, the older the subject, the more likely is behavioral awakening. The response rates to the two types of stimuli were essentially the same. The stimulus intensity had little, if any, effect on frequency of arousal, although other degrees of response did increase.

Lukas, J. S.↗

NASA NTRS1971