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Subjective equivalence of sinusoidal and random whole-body vibration
Journal of Sound and Vibration (1977) 52(4), 6 15-6 17
HUMAN
RESPONSE TO VIBRATION ABSTRACTS
Prepared by M. J. Grifin and J. Grifin, Human Factors Research Unit, Institute of Sound and Vibration Research, University of Southampton, Southampton SO9 5NH, England
R. W. Shoenberger 1975 Aviation, Space and Environmental Medicine 46,785-790. Subjective response to very low-frequency vibration. (6 pages, 6 figures, 2 tables, 11 references) Author’s Abstract. Using intensity matching and magnitude estimation techniques, seated subjects made judgments of the perceived intensity of vertical, short duration (30-60 s), high-amplitude, low-frequency (0.25-4.0 Hz) vibration. Intensity matching (setting comparison frequencies to match the perceived intensity of a standard frequency) produced equal intensity contours that indicated minimum sensitivity in the vicinity of 1 Hz. Frequencies both above and below 1 Hz werejudged subjectively equal at progressively lower accelerations. In the magnitude estimation procedure, subjects assigned values of subjective magnitude to various levels of a given frequency in proportion to the subjective magnitude of a standard level at the same frequency. For each of seven frequencies sampled, the data produced straightline functions on log-log plots of subjective magnitude vs. acceleration. Data from both the intensity matching and magnitude estimation experiments were combined to provide a model that allowed the extension of various vibration exposure criteria down to 0.25 Hzusing data at 4 Hz as a basis for extrapolation-even at intensity levels beyond the capabilities of available vibration devices. Topics : Subjective Assessment (Intensity Matching, Magnitude Estimation). R. L. Stalnaker, J. L. Fogle and J. H. McHaney 1971 Journalof Biomechanics 4, 127-139. Driving point impedance characteristics of the head. (13 pages, 14 figures, 2 tables, 14 references) Authors’ Abstract. The mechanical impedance of the human and monkey (Mucaca mulatta) head was determined over the frequency range 30-5000 Hz. Miniature accelerometers and pressure transducers were placed in the brain to measure its response to vibration at constant g-levels and variable frequency. The maximum acceleration studied was 20 g’s. In vitro experiments on a fresh human cadaver and in vivo and in vitro experiments on monkeys were performed. The effect of varying blood pressure was investigated as well as the contribution to the mechanical impedance of the scalp, skull and brain. A linear two-degree-of-freedom model that summarizes the results with acceptable accuracy is presented. Certain non-linear responses were observed for various input accelerations. No significant effect on impedance due to time after death was found for times up to five hours. The implantable accelerometer and pressure transducer experiments indicated that the brain is very nearly critically damped. Raising the blood pressure was shown to stiffen the brain, causing the resonance frequency of the head to increase. Topics : Biodynamics (Mechanical Impedance, Body Resonance); Head Vibration; Non-human Subjects (Monkeys).
M. J. Griffin 1976 Journal of the Acoustical
Society
of America
60, 1140-l 145. Subjective
616
HUMAN RESPONSE TO VIBRATION
equivalence of sinusoidal and random whole-body vibration. (6 pages, 4 figures, 3 tables, 12 references) Author’s Abstract. An experiment conducted to compare the discomfort produced by wholebody sinusoidal vibration with that produced by one-third, one-, and three-octave spectra is described. Seated subjects were required to adjust the level of a variable test vibration such that it produced a degree of discomfort similar to that caused by a 10 Hz sinusoidal vertical whole-body vibration at 0.75 m/s’ r.m.s. The test stimuli were nine sinusoidal vibrations (at 3.15,4.00, .5*00,6.30,8.00, 10.00, 12.50, 16.00 and 20 Hz); nine one-third-octave bands of random vibration centered at the above frequencies, three single-octave bands (centered at 4.00,8.00 and 16.00 Hz) and a three-octave band (centered at 8.00 Hz). The results obtained by this method indicate that the mean equivalent discomfort produced by all random motions employed in this experiment may be predicted by weighting the vibration spectra with a filter network. A suitable filter response is that determined from a contour of equal comfort for sinusoidal or one-third octave random vibration. Topics: Subjective Assessment (Intensity Matching); Complex Vibration (Random); Criteria and Limits J. H. Kirman 1973 Psychological Bulletin 80, 54-74. Tactile communication of speech: A review and an analysis. (21 pages, 93 references) Author’s Abstract. This paper reviews attempts to present the acoustic speech signal to the skin by means of various electromechanical devices. Explanations for the relative failure of these speech-to-tactile transformations are critically examined: first, a current theory that speech is a special code necessarily incomprehensible to the skin, and second, evidence that tactile masking effects preclude analysis of a signal as complex as speech by the skin. Both of these explanations are rejected, and it is suggested that the displays reviewed failed to provide the stimulus structure necessary for effective tactile perception. The stimulus requirements for perceptual organization by the skin of various levels of linguistic structure are discussed. Suggestions are then made for the future development of tactile displays of speech that may be comprehended at rapid rates. Topics: Vibration Sense (Communication, Masking). R. G. Edwards and C. F. Knapp 1973 Aerospace Medicine 44, 910-913. Changes in whole body force transmission of dogs exposed repeatedly to vibration. (4 pages, 4 figures, 12 references) Authors’ Abstract. Whole body force transmission was recorded from sitting dogs during 30-s exposures to vertical, sinusoidal vibration. A vibration test consisted of sequentially exposing each animal to frequencies of 2, 3, 4, 5, 6, 7 and 12 Hz at constant acceleration amplitudes from 0.3 to 1.0 g. Each test was repeated approximately every 2 days. Whole body force transmission was plotted as a function of vibration frequency and repeated exposure to the same vibration. Analysis of the data indicated appreciable changes in the amplitude of whole-body force transmission from repeated exposures near the resonant frequency. For this case, the largest value of force transmission occurred during the first test and decreased to lower values with repeated exposure. A 36 y0 reduction in transmitted force from the initial to the seventh exposure was observed from one of the animals during 4 Hz vibration at 0.7 g. Topics : Biodynamics (In General); Non-human Subjects (Dogs). T. Fukuda 1975 Acta Otolaryngolica Supplement 330, 9-14, Postural behavior and motion sickness. (6 pages, 6 figures, 3 references) Author’s Abstract. An interesting style of acting was demonstrated on a stage of a Kyogen, a
HUMAN
RESPONSE TO VIBRATION ABSTRACTS
Prepared by M. J. Grifin and J. Grifin, Human Factors Research Unit, Institute of Sound and Vibration Research, University of Southampton, Southampton SO9 5NH, England
R. W. Shoenberger 1975 Aviation, Space and Environmental Medicine 46,785-790. Subjective response to very low-frequency vibration. (6 pages, 6 figures, 2 tables, 11 references) Author’s Abstract. Using intensity matching and magnitude estimation techniques, seated subjects made judgments of the perceived intensity of vertical, short duration (30-60 s), high-amplitude, low-frequency (0.25-4.0 Hz) vibration. Intensity matching (setting comparison frequencies to match the perceived intensity of a standard frequency) produced equal intensity contours that indicated minimum sensitivity in the vicinity of 1 Hz. Frequencies both above and below 1 Hz werejudged subjectively equal at progressively lower accelerations. In the magnitude estimation procedure, subjects assigned values of subjective magnitude to various levels of a given frequency in proportion to the subjective magnitude of a standard level at the same frequency. For each of seven frequencies sampled, the data produced straightline functions on log-log plots of subjective magnitude vs. acceleration. Data from both the intensity matching and magnitude estimation experiments were combined to provide a model that allowed the extension of various vibration exposure criteria down to 0.25 Hzusing data at 4 Hz as a basis for extrapolation-even at intensity levels beyond the capabilities of available vibration devices. Topics : Subjective Assessment (Intensity Matching, Magnitude Estimation). R. L. Stalnaker, J. L. Fogle and J. H. McHaney 1971 Journalof Biomechanics 4, 127-139. Driving point impedance characteristics of the head. (13 pages, 14 figures, 2 tables, 14 references) Authors’ Abstract. The mechanical impedance of the human and monkey (Mucaca mulatta) head was determined over the frequency range 30-5000 Hz. Miniature accelerometers and pressure transducers were placed in the brain to measure its response to vibration at constant g-levels and variable frequency. The maximum acceleration studied was 20 g’s. In vitro experiments on a fresh human cadaver and in vivo and in vitro experiments on monkeys were performed. The effect of varying blood pressure was investigated as well as the contribution to the mechanical impedance of the scalp, skull and brain. A linear two-degree-of-freedom model that summarizes the results with acceptable accuracy is presented. Certain non-linear responses were observed for various input accelerations. No significant effect on impedance due to time after death was found for times up to five hours. The implantable accelerometer and pressure transducer experiments indicated that the brain is very nearly critically damped. Raising the blood pressure was shown to stiffen the brain, causing the resonance frequency of the head to increase. Topics : Biodynamics (Mechanical Impedance, Body Resonance); Head Vibration; Non-human Subjects (Monkeys).
M. J. Griffin 1976 Journal of the Acoustical
Society
of America
60, 1140-l 145. Subjective
616
HUMAN RESPONSE TO VIBRATION
equivalence of sinusoidal and random whole-body vibration. (6 pages, 4 figures, 3 tables, 12 references) Author’s Abstract. An experiment conducted to compare the discomfort produced by wholebody sinusoidal vibration with that produced by one-third, one-, and three-octave spectra is described. Seated subjects were required to adjust the level of a variable test vibration such that it produced a degree of discomfort similar to that caused by a 10 Hz sinusoidal vertical whole-body vibration at 0.75 m/s’ r.m.s. The test stimuli were nine sinusoidal vibrations (at 3.15,4.00, .5*00,6.30,8.00, 10.00, 12.50, 16.00 and 20 Hz); nine one-third-octave bands of random vibration centered at the above frequencies, three single-octave bands (centered at 4.00,8.00 and 16.00 Hz) and a three-octave band (centered at 8.00 Hz). The results obtained by this method indicate that the mean equivalent discomfort produced by all random motions employed in this experiment may be predicted by weighting the vibration spectra with a filter network. A suitable filter response is that determined from a contour of equal comfort for sinusoidal or one-third octave random vibration. Topics: Subjective Assessment (Intensity Matching); Complex Vibration (Random); Criteria and Limits J. H. Kirman 1973 Psychological Bulletin 80, 54-74. Tactile communication of speech: A review and an analysis. (21 pages, 93 references) Author’s Abstract. This paper reviews attempts to present the acoustic speech signal to the skin by means of various electromechanical devices. Explanations for the relative failure of these speech-to-tactile transformations are critically examined: first, a current theory that speech is a special code necessarily incomprehensible to the skin, and second, evidence that tactile masking effects preclude analysis of a signal as complex as speech by the skin. Both of these explanations are rejected, and it is suggested that the displays reviewed failed to provide the stimulus structure necessary for effective tactile perception. The stimulus requirements for perceptual organization by the skin of various levels of linguistic structure are discussed. Suggestions are then made for the future development of tactile displays of speech that may be comprehended at rapid rates. Topics: Vibration Sense (Communication, Masking). R. G. Edwards and C. F. Knapp 1973 Aerospace Medicine 44, 910-913. Changes in whole body force transmission of dogs exposed repeatedly to vibration. (4 pages, 4 figures, 12 references) Authors’ Abstract. Whole body force transmission was recorded from sitting dogs during 30-s exposures to vertical, sinusoidal vibration. A vibration test consisted of sequentially exposing each animal to frequencies of 2, 3, 4, 5, 6, 7 and 12 Hz at constant acceleration amplitudes from 0.3 to 1.0 g. Each test was repeated approximately every 2 days. Whole body force transmission was plotted as a function of vibration frequency and repeated exposure to the same vibration. Analysis of the data indicated appreciable changes in the amplitude of whole-body force transmission from repeated exposures near the resonant frequency. For this case, the largest value of force transmission occurred during the first test and decreased to lower values with repeated exposure. A 36 y0 reduction in transmitted force from the initial to the seventh exposure was observed from one of the animals during 4 Hz vibration at 0.7 g. Topics : Biodynamics (In General); Non-human Subjects (Dogs). T. Fukuda 1975 Acta Otolaryngolica Supplement 330, 9-14, Postural behavior and motion sickness. (6 pages, 6 figures, 3 references) Author’s Abstract. An interesting style of acting was demonstrated on a stage of a Kyogen, a