Future Directions for Research on the Combined Effects of Noise and Vibration on Cognition and Communication
Future Directions for Research on the Combined Effects of Noise and Vibration on Cognition and Communication

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Published: 2004

Total Pages: 2

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In order to gain a better understanding of how to optimize the performance of personnel operating military vehicles, where exposure to noise & vibration is a problem, it is important to consider the effects of realistic levels of noise & vibration. This paper presents an overview of previous studies of communication & cognitive performance in noise & vibration, including studies of speech intelligibility in noise and of the effects of whole body vibration, noise, and their combination on task performance. It also suggests directions for future research.

Combined Effects of Noise and Vibration on Mental Performance
Combined Effects of Noise and Vibration on Mental Performance

Author: C. Stanley Harris

Publisher:

Published: 1971

Total Pages: 20

ISBN-13:

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Two experiments were conducted to determine the combined effects of noise and vibration on mental performance. In experiment 1, ten subjects were tested on a combination short term memory and subtraction task during exposure to four different intensities of broadband noise. Another group of ten subjects was tested using the same noise intensities in combination with 0.25g (peak) vertical vibration at 5Hz. Noise alone, and vibration with low level noise (80 dB and 90 dB re 0.0002 dyne/sq cm) had no adverse effects on task performance while the highest level of noise (110 dB) combined with vibration to produce a significant reduction in the number of correct responses. In experiment 2, the second group of subjects used in experiment 1 was tested during exposure to the following conditions: no vibration (control), vibration at 5 Hz - 0.25g, 7 Hz - 0.30g, and 11 Hz - 0.50g, all combined with 80 dB noise. Subsequently these same vibration conditions were presented with 107 dB noise. High intensity noise and vibration combined to produce a greater decrement in performance than either stressor alone. Vibration at 5 Hz was a more sensitive frequency for mental subtraction performance than 7Hz and 11 Hz when the three frequencies were presented in conjunction with high intensity noise. (Author).

Combined Effects of Noise and Vibration on Mental Performance as a Function of Time of Day
Combined Effects of Noise and Vibration on Mental Performance as a Function of Time of Day

Author: Henry C. Sommer

Publisher:

Published: 1970

Total Pages: 15

ISBN-13:

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To determine the combined effects of noise and vibration on mental performance as a function of time of day, subjects were randomly exposed to each of the following conditions: stress (5 Hz vibration, 110 dB noise) at 6 AM; no stress (no vibration - 85 dB noise) at 6 AM; stress at 3 PM; and no stress at 3 PM. Subjects' performance on a mental arithmetic task was measured during each of these exposures on consecutive days. The average exposure time was approximately 20 minutes. The results are discussed in the context of arousal theory. (Author).

The Combined Effects of Vibration, Noise, and Exposure Duration on Auditory Temporary Threshold Shift
The Combined Effects of Vibration, Noise, and Exposure Duration on Auditory Temporary Threshold Shift

Author: Henry C. Sommer

Publisher:

Published: 1973

Total Pages: 20

ISBN-13:

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To determine the combined effects of noise and vibration on auditory function, the temporary threshold shifts (TTS) of two groups of 10 subjects each were measured as a function of intensity and duration of exposure. Combined noise and vibration was presented to one group for 5 minutes and to the other for 20 minutes. Both groups were exposed to vibration in the Z axis at frequencies of 9 Mz and 18 Hz at intensity levels of 0.475 gz (peak) and 0.950 gz, respectively. Noise levels of 90 dB and 100 dB were presented simultaneously with the vibration. TTS was measured at post exposure recovery times of 0.5, 2.0, 5.0, 10.0, and 20.0 minutes. Although the mean difference was small (0.72 dB), a significantly larger TTS was obtained at 9 Hz than 18 Hz vibration, and 100 dB produced a larger TTS than 90 dB. Significant differences in TTS were also obtained as a function of duration of exposure, and as a function of post exposure recovery time. (Modified author abstract).

Combined Effects of Noise and Vibration on Psychomotor Performance
Combined Effects of Noise and Vibration on Psychomotor Performance

Author: C. Stanley Harris

Publisher:

Published: 1970

Total Pages: 29

ISBN-13:

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Tracking performance and reaction time to the appearance of a light (red lights) and disappearance of a light (green lights) of highly trained subjects were measured during four experimental conditions. There were two conditions of 85 dB and 110 dB broadband noise exposure, and two conditions in which these noise exposures were combined with 0.25G vertical vibration at 5 Hz. Duration of exposure for each condition was 19 minutes. Vibration was found to have an adverse effect on both the horizontal and vertical dimensions of the tracking task and on reaction time to both sets of lights. Noise had a significant effect, both with and without vibration, but only on the vertical part of the tracking task. On vertical tracking, the detrimental effect of noise was additive to that of vibration when both noise and vibration were presented simultaneously (110dB noise and 0.25G vertical vibration at 5 Hz). (Author).