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or calculation task
Journal of Sound and Vibration (1995) 186(4), 599–605
A PHYSIOLOGICAL RESPONSE (PLASMA CYCLIC AMP) AND A PSYCHOLOGICAL RESPONSE (STAI-A-STATE) TO NOISE EXPOSURE AND/OR CALCULATION TASK M. I, F. I, J. Y, T. M N. H Department of Hygiene, Yamaguchi University School of Medicine, 1144 Kogushi, Nishiku UBE 755, Yamaguchi Prefecture, Japan (Received 21 October 1993, and in final form 19 October 1994)
The effects of 90 dB(A) noise exposure and/or a calculation task on plasma cyclic AMP concentrations (physiological index) and STAI-A-State scores (psychological index) in normal subjects are compared. Neither the plasma cyclic AMP concentration nor the STAI-A-State scores showed any significant change in response to the calculation task. STAI-A-State scores increased significantly only in response to 90 dB(A) noise exposure, while both the indices showed significant increases under the effects of both noise exposure and the calculation task. The sensitivity of the rate of increase in plasma cyclic AMP caused by noise exposure plus the calculation task was higher than that of the rate of increase in scores on the A-State scale caused by this noise exposure/task combination. The physiological effect in human subjects of noise exposure became larger when a psychological stress (calculation task) was added. 7 1995 Academic Press Limited
1. INTRODUCTION
Hypothalamo-hypophyseal-adrenal responses to noise in rats were reported by Henkin et al. [1], Arizono et al. [2] and Anthony et al. [3]. Hormonal responses to noise in humans, reported by Arguelles et al. [4], were increased excretion of urinary catecholamines and increased concentration of plasma 17-hydroxycorticoids. Brandenberger et al. [5, 6] and Favino et al. [7], however, found no increase in plasma cortisol during stimulation by noise. Andren et al. [8] also reported that noise stimulation (95 dB(A)) for 20 minutes did not have any effect on the secretion of adrenaline, noradrenaline, prolactin, growth hormone (GH) and cortisol in man. In our previous experiment on human subjects, plasma cortisol, FSH (follicle-stimulating hormone) and LH (luteinizing hormone) levels did not change due to 100 dB(A) noise exposure alone, unlike the case for rats. We thought that the difference between these reactions in humans and rats was based on a difference in anxiety in response to noise stressors. Accordingly, we examined the effects of noise and a calculation task in human subjects. We found that the combined effect of these stressors on plasma cortisol and anterior pituitary hormones such as GH, prolactin and ACTH were evident at over 85 dB(A), whereas the changes induced in plasma cyclic AMP concentrations were detectable at lower levels of noise exposure (70 dB(A)) when the calculation task was added to the noise exposure [9]. Thus, plasma cyclic AMP which has been advocated as a second messenger of various 599 0022–460X/95/390599+07 $12.00/0
7 1995 Academic Press Limited
600
. ET AL .
hormones by Sutherland et al. [10–12] was a sensitive index for noise-related stress in human subjects. It reflects autonomic nervous functions [13], central nervous functions and hormone secretion resulting from the stimulation of many receptors. In our previous study [14], we used the State-Trait Anxiety Inventory (STAI) developed by Spielberger [15] and investigated the validity and reliability of both these scales, that is A-state and A-trait, and at the same time examined them under various conditions. We have found that noise exposure of over 75 dB(A) plus a calculation task increased A-State scores, but that the individual differences in responses were large. In this study we have examined the effects of noise exposure and/or a calculation task on plasma cyclic AMP concentration and STAI-A-State scores. We used these two indices because they can measure reaction to noise stressors, plasma cyclic AMP being a physiological index and A-State being a psychological index. We examined points of agreement and differences in results obtained by using these indices in the effects of only the calculation task, only noise exposure and noise exposure plus calculation task. The rates of increase in plasma cyclic AMP and changes in A-State scores after noise exposure plus the calculation task as stress indices were examined in relation to their sensitivity and specificity. 2. SUBJECTS AND METHODS
The subjects were 154 female student volunteers, aged 18 to 19 years, with normal hearing ability: 19 subjects were placed in the control group, 28 in the calculation group, 21 in the noise group and 86 in the noise plus calculation group by random selection. On the day of the experiment, they were required to stay in a quiet room from noon onwards (light conversation and reading being permitted). At 3:00 p.m. subjects were taken into a noise laboratory which had a background noise level of less than 40 dB(A), temperature between 23°C and 25°C and humidity between 60% and 80%. The subjects in the noise group were exposed to acoustic stimulation (90 dB(A) pink noise) for 15 minutes, with alternating ON time of 55 s and OFF time of 5 s. The ‘‘pink noise’’ was generated by a Rion Generator (SF-04) and further magnified with an amplifier (SS-02) to 90 dB(A). Pink noise was chosen for this study as it has a frequency characteristic of octave −3 dB, consists of many frequencies and is similar to environmental and industrial noise. The noise exposure level used was 90 dB(A), which is not usual for the general environment but is common in the indusrial environment. Each subject in the calculation and in the noise plus calculation groups was requried to execute 20 multiplication problems each consisting of three figures in 15 minutes. Before and immediately after noise exposure and/or calculation task, blood samples were drawn into test tubes containing EDTA-Na. These samples were centrifuged immediately after collection, and the plasma was frozen and stored at −20°C until assayed. Plasma cyclic AMP was measured by radioimmunoassay, using a YAMASA Cyclic AMP kit. The STAI-A-State also was measured before and after noise exposure and/or calculation task. The STAI-A-State that we used was a questionnaire developed by Spielberger [16] and translated into Japanese by Toyama [17]. We have previously reported the methods for carrying out measurements on this STAI-A-State scale in detail [14]. The questionnaires requested a four-stage reply. On this scale, the larger the score, the higher the anxiety; the total score of the A-State is from 20 to 80 points. The student volunteers in the control group were not subjected to noise exposure and were given no calculation task. The other conditions for the control group were the same as those for the other groups. Plasma cyclic AMP and A-State were measured in the control group as in other groups.
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3. RESULTS
In Table 1 are shown plasma cyclic AMP concentrations, the rates of change in plasma cyclic AMP, the A-State score, and the rates of change in the A-State scores in the control, calculation, noise and noise plus calculation groups. In the calculation group, neither plasma cyclic AMP concentration nor the A-State score showed any significant change compared with pre-task values. In the noise group, the A-State score increased significantly after noise exposure compared with pre-noise exposure values (pQ0·001), while in the noise plus calculation group, both plasma cyclic AMP concentration and A-State score increased significantly compared with pre-exposure values (pQ0·001). In the noise group, the rate of increase in A-State score was significantly (pQ0·001) larger than that in the control group, but the rate of increase in plasma cyclic AMP did not change significantly. The rates of increases in plasma cyclic AMP and A-State score in the combined group were significantly larger than those in the control group (pQ0·001 and pQ0·01). The pre-exposure A-State score in the noise plus calculation group was significantly larger than that in other groups. All subjects in the control group had A-State scores below 42, while some in the noise plus calculation group had more than 42. The ratio of the pre-exposure A-State score to the post-exposure A-State score is statistically significant in the noise and noise plus calculation groups. In Table 2 is shown further classification of the noise plus calculation group based on the pre-exposure A-State score being q42 or E42. The plasma cyclic AMP concentration, the rates of change in the plasma cyclic AMP, the A-State score and the rates of change in the A-State scores are shown. The rate of increase in A-State score in the q42 group was significantly smaller than that in the E42 group (pQ0·01). When comparing the noise plus calculation group with the only noise group, the rate of increase in the A-State score in the E42 group was not significantly different.
T1 Plasma cyclic AMP concentrations and A-State scores in control, calculation, noise and noise plus calculation groups Group ZXXXXXXXXXXXXXXCXXXXXXXXXXXXXXV Noise plus Control Calculation Noise calculation (n=19) (n=28) (n=21) (n=86) (1) c-AMP(pmol/ml) (pre-exposure) (2) c-AMP(pmol/ml) (post-exposure) (3) ((2)−(1)) (4) ((2)/(1)) (5) A-State score (pre-exposure) (6) A-State score (post-exposure) (7) ((6)−(5)) (8) ((6)/(5))
11·1722·04
11·6622·12
11·5821·54
11·8822·27
11·1721·81 NS
11·9021·40 NS
12·1421·50 NS
15·0123·07***
0·0021·05 1·0120·09 33·5825·76
0·2521·74 1·0420·15 35·0727·10
0·5621·42 1·0620·12 34·6225·12
3·1222·95((( 1·2920·29((( 40·5728·74&&
36·1127·31 NS
36·2926·87 NS
48·71210·30***
49·93211·06***
14·10210·64((( 1·4320·36(((
9·36211·47((( 1·2720·33((
2·5326·46 1·0920·21
1·2126·88 1·0620·20
Values are means 2 S.D. ***, pQ0·001 before and after the respective exposure (paired t-test). NS, Not significant before and after the respective exposure (paired t-test). ((( , pQ0·001 to control (Student’s t-test). (( , pQ0·01 to control (Student’s t-test). && , pQ0·01 to A-State scores (pre-exposure) in control, calculation and noise groups (Student’s t-test).
. ET AL .
602
T 2 Plasma cyclic AMP concentrations and A-State scores in noise plus calculation groups Noise plus calculation group ZXXXXXXXXXXXCXXXXXXXXXXXV A-State score A-State score (pre-exposure)E42 (pre-exposure)q42 (n=53) (n=33) (1) (2) (3) (4) (5) (6) (7) (8)
c-AMP (pre-exposure) c-AMP (post-exposure) ((2)−(1)) ((2)/(1)) A-State score (pre-exposure) A-State score (post-exposure) ((6)−(5)) ((6)/(5))
11·7722·39 14·7922·78*** 3·0222·86 1·2920·29 35·0224·58 47·46210·36*** 12·44210·58 1·3720·34
12·0622·09 15·3523·50*** 3·2923·13 1·2920·31((( 49·4825·97((( 53·89211·14* 4·41211·26(( 1·1020·23(((
Values are means 2S.D. ***, pQ0·001 before and after the respective exposure (paired t-test). *, pQ0·05 before and after the respective exposure (paired t-test). ((( , pQ0·001 to (A-State score (pre-exposure)E42) group (Student’s t-test). (( , pQ0·01 to (A-State score (pre-exposure)E42) group (Student’s t-test).
Coefficients of correlation between each examined item for the 86 subjects in the noise plus calculation group are shown in Table 3. In the combined group the rates of increase in plasma cyclic AMP and A-State frequently exceeded the 90% upper confidence interval of the controls. The specificities and sensitivities of the two indices are shown in Table 4. The criteria used in this table were the 90% and 95% upper confidence intervals in the controls. The sensitivity of the rate of increase in plasma cyclic AMP was 67·4% and that of A-State 26·7% when the specificity was about 90%. 4. DISCUSSION
We have reported that plasma cyclic AMP concentration in human subjects increased under noise exposure of over 70 dB(A) plus a claculation task [9]. Human plasma anterior pituitary hormones change only a little in response to the above stressors and therefore this
T 3 Correlation matrix (noise plus calculation group n=86) (1) (1) (2) (3) (4) (5) (6) (7) (8)
c-AMP (pre-exposure) c-AMP (post-exposure) ((2)−(1)) ((2)/(1)) A-State score (pre-exposure) A-State score (post-exposure) ((6)−(5)) ((6)/(5))
**, pQ0·01 (between two indices). *, pQ0·05 (between two indices).
(2)
(3)
(4)
(5)
(6)
(7)
0·42** −0·33** 0·72** −0·45** 0·59** 0·96** 0·06 0·09 0·04 0·01 −0·02 0·00 0·02 0·00 0·35** −0·05 −0·06 −0·02 −0·01 −0·43** 0·70** −0·07 −0·07 −0·04 −0·03 −0·51** 0·59** 0·96**
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603
T 4 Specificities and sensitivities of the rates of increases in plasma cyclic AMP concentration and A-State score (C group=control group, NC group=noise plus calculation group, C.I.=confidence interval in control group)
Criterion
Specificity C group (n=19)(%)
Sensitivity NC group (n=86)(%)
The rate of increase of plasma cyclic AMP
90% upper C.I. 95% upper C.I.
89·5 94·7
67·4 61·6
The rate of increase of A-state score
90% upper C.I. 95% upper C.I.
89·5 89·5
26·7 24·4
change is not detected. On the other hand, changes in plasma cyclic AMP, which we believed to be a sensitive index to noise plus calculation task, were certainly detectable. We have already reported [14] that anxiety increases after exposure to various noise levels plus calculation task. We measured scores on the A-State scale before and after various noise exposures plus calculation task. The A-State score increased significantly by short-term noise exposure of over 75 dB(A) plus a calculation task. The rate of increase in A-State scores was found to occur in direct proportion to the noise exposure level. In our human subjects, noise of more than 75 dB(A) plus a calculation task caused psychological reactions that were different from those caused by noise of less than 70 dB(A) plus a calculation task. However, in our previous study, we did not discuss the effects of only the calculation task or only the noise exposure in human subjects. In the present study, the effects of the above stressors in human subjects were examined both separately as well as simultaneously. Twenty multiplication problems consisting of three figures each were used to produce the stressful condition in combination with noise exposure. The subjects had to execute these problems in 15 minutes. However, these calculations may not have been stressful because A-state score in the subjects did not increase under calculation task alone. There are several reports on performance effects of noise. Harris [18] reported that random and fixed intermittent sound (from 85 dB(A) to 105 dB(A)) did not affect calculation performance. Edsell [19] has pointed out that although the effects of noise on human behavior have been examined experimentally for over 30 years, these studies have usually considered noise as the only independent variable [20] and that studies of multiple stressors involving noise [20, 21] indicate that the combined effects are sometimes synergistic and sometimes antagonistic and that results are often unpredictable. From short-term exposure studies, Mosskov et al. [22] suggested that even noise exposure below 85 dB(A) increased diastolic pressure and catecholamine excretion. However, Lundberg et al. [23] reported that even under well-controlled conditions the results varied depending on the additional load to which the experimental subjects were exposed. Lamp [24] reported that for tasks in which voice communication was unnecessary, the effects of noise on performance appear to depend on the characteristics of the noise, the type of task, and the attitude and personality of the worker, and that the general conclusions usually were as follows: steady state noise under 90 dB(A) does not seem to interfere with work performance. Above 90 dB(A), the results are inconsistent. In a community-based cross-sectional study, Lercher [25] suggested that the public health impact of noisy working conditions, aside from hearing loss, can be underestimated when combined effects were not adequately considered.
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. ET AL .
In this study we did not find any difference in the psychological effects induced by 90 dB(A) noise exposure alone and noise plus the calculation task, but the physiological response to the calculation task performed in presence of noise exposure was significantly larger than that due to the noise exposure alone. The present data show that a physiological effect in human subjects under noise exposure can become larger when a psychological stress (calculation task) is added. The pre-exposure A-State score in the noise plus calculation group was larger than that in the noise group. The subjects in this group may have anticipated a stress situation after discussions with their friends who had done the test. Compared to the control group, the rate of increase in the A-State score in the noise group was larger (pQ0·001) than that in the noise plus calculation group (pQ0·01). Sensitivity and specificity in screening tests have been defined by Thamer [26]. These are also used for the determination of the efficacy of screening by medical examination. The normal value is important in determining the efficacy of screening. The normal range is expressed by using the mean value and the standard deviation for healthy persons. In our results, we found that the sensitivity of the rate of increase in plasma cyclic AMP was larger than that of the rate of increase in the A-State score in the noise plus calculation group. In this group the rate of increase in plasma cyclic AMP exceeded the 90% upper confidence interval in the control group in 67%, and the rate of increase in A-State in 27%. The coefficient of correlation between the rates of increases in the A-state score and the plasma cyclic AMP was not significant. The agreement of physiological reaction and psychological reaction to the noise exposure under mental stress was low. We used two types of tests which gave rather similar results, but the intercorrelation was not good. This could mean that certain individuals reacted in the psychological test and others in the physiological test. This would appear to depend on the personality of the subjects. REFERENCES 1. R. I. H and K. M. K 1963 American Journal of Physiology 204, 710–714. Effect of sound on the hypothalamic–pituitary–adrenal axis. 2. H. A, M. I and Y. T 1976 Journal of the Aichi Medical University Association 4(1), 1–5. Hypothalamo-hypophyseal-adrenal response to noise (threshold limit value for white noise). 3. A. A, N. W. B and G. J. C 1979 Journal of Histochemistry and Cytochemistry 27(10), 1380–1381. Cytochemical bioassay and radioimmunoassay of ACTH in noise stressed rats. 4. A. E. A, D. I, J. P. O and M. C 1962 Journal of Clinical Endocrinology and Metabolism 22, 846–852. Pituitary-adrenal stimulation by sound of different frequencies. 5. G. B, M. F and C. T 1977 European Journal of Applied Physiology 36, 239–246. Failure of noise exposure to modify temporal patterns of plasma cortisol in man. 6. G. B, M. F, G. W and P. S 1980 Biological Psychology 10, 239–252. Plasma catecholamines and pituitary adrenal hormones related to mental task demand under quiet and noise conditions. 7. A. F, A. T, L. B, A. M, C. A and G. P 1975 Medicina del Lavoro 66(2), 109–118. ACTH and corticoids levels in plasma with contemporaneous EEG changes during noise in man. 8. L. A, G. L, M. B, K. O. B and L. H 1982 Clinical Science 62, 137–141. Effect of noise on blood pressure and stress hormones. 9. M. I, H. D, F. I, J. Y, S. Y and H. G 1988 Journal of Sound and Vibration 127, 431–439. The plasma cyclic-AMP response to noise in human and rats (short-term exposure of various noise levels). 10. E. W. S and T. W. R 1960 Pharmacological Reviews 12, 265–299. The relation of adenosine-3',5'-phosphate and phosphorylase to the actions of catecholamines and other hormones.
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11. E. W. S, G. A. R and R. W. B 1968 Circulation 37, 279–306. Some aspects of the biological role of adenosine-3',5'-monophosphate (cyclic AMP). 12. G. A. R, R. W. B and E. W. S 1968 Annual Reviews of Biochemistry 37, 149–174. Cyclic AMP. 13. N. H, H. K and K. K 1990 British Journal of Industrial Medicine 147, 263–268. Assessment of autonomic nervous function in patients with vibration syndrome using heart rate variation and plasma cyclic nucleotides. 14. M. I, H. D, J. Y, F. I, H. G and T. M 1989 Japanese Journal of Hygiene 43, 1116–1123. A study of the state-trait anxiety inventory (STAI) and its application to noise stress. 15. C. D. S (editor) 1966 Anxiety and Behaviour. New York: Academic Press. 16. C. D. S, R. L. G and R. E. L 1970 STAI Manual. California: Consulting Psychologists Press. 17. N. T, Y. C and K. S 1976 Proceedings of the 40th Annual Meeting of the Japanese Society for Psychology, 891–892. A study on state-trait anxiety inventory. 18. C. S. H 1976 Aerospace Medical Laboratory-TR-76-7, 1–9. Aftereffects of random and fixed intermittent sound on human performance. 19. R. D. E 1976 Journal of Psychology 92, 219–226. Anxiety as a function of environmental noise and social interaction. 20. D. E. B 1963 Quarterly Journal of Experimental Psychology 15, 205–211. Differences and interactions between stresses. 21. W. P. C and R. S. E 1975 Ergonomics 18, 81–87. Interaction of noise with alcohol on a task of sustained attention. 22. J. I. M and J. H. E 1977 International Archives of Occupational and Environmental Health 40, 165–184. Extra-auditory effects in short-term exposure to noise. 23. U. L and M. F 1978 Biological Psychology 6(1), 51–59. Psychophysiological reactions to noise as modified by personal control over noise intensity. 24. F. M. L 1981 Forest Products Journal 31(1), 48–53. Performance and annoyance effects of noise. 25. P. L, J. H and W. K 1993 International Archives of Occupational and Environmental Health 65, 23–28. Work noise annoyance and blood pressure: combined effects with stressful working conditions. 26. M. A. T, J. C. H and J. W. R 1962 Journal of the Chronic Diseases 15, 835–847. Development of a multiphasic screening examination for medical care patients—II.
A PHYSIOLOGICAL RESPONSE (PLASMA CYCLIC AMP) AND A PSYCHOLOGICAL RESPONSE (STAI-A-STATE) TO NOISE EXPOSURE AND/OR CALCULATION TASK M. I, F. I, J. Y, T. M N. H Department of Hygiene, Yamaguchi University School of Medicine, 1144 Kogushi, Nishiku UBE 755, Yamaguchi Prefecture, Japan (Received 21 October 1993, and in final form 19 October 1994)
The effects of 90 dB(A) noise exposure and/or a calculation task on plasma cyclic AMP concentrations (physiological index) and STAI-A-State scores (psychological index) in normal subjects are compared. Neither the plasma cyclic AMP concentration nor the STAI-A-State scores showed any significant change in response to the calculation task. STAI-A-State scores increased significantly only in response to 90 dB(A) noise exposure, while both the indices showed significant increases under the effects of both noise exposure and the calculation task. The sensitivity of the rate of increase in plasma cyclic AMP caused by noise exposure plus the calculation task was higher than that of the rate of increase in scores on the A-State scale caused by this noise exposure/task combination. The physiological effect in human subjects of noise exposure became larger when a psychological stress (calculation task) was added. 7 1995 Academic Press Limited
1. INTRODUCTION
Hypothalamo-hypophyseal-adrenal responses to noise in rats were reported by Henkin et al. [1], Arizono et al. [2] and Anthony et al. [3]. Hormonal responses to noise in humans, reported by Arguelles et al. [4], were increased excretion of urinary catecholamines and increased concentration of plasma 17-hydroxycorticoids. Brandenberger et al. [5, 6] and Favino et al. [7], however, found no increase in plasma cortisol during stimulation by noise. Andren et al. [8] also reported that noise stimulation (95 dB(A)) for 20 minutes did not have any effect on the secretion of adrenaline, noradrenaline, prolactin, growth hormone (GH) and cortisol in man. In our previous experiment on human subjects, plasma cortisol, FSH (follicle-stimulating hormone) and LH (luteinizing hormone) levels did not change due to 100 dB(A) noise exposure alone, unlike the case for rats. We thought that the difference between these reactions in humans and rats was based on a difference in anxiety in response to noise stressors. Accordingly, we examined the effects of noise and a calculation task in human subjects. We found that the combined effect of these stressors on plasma cortisol and anterior pituitary hormones such as GH, prolactin and ACTH were evident at over 85 dB(A), whereas the changes induced in plasma cyclic AMP concentrations were detectable at lower levels of noise exposure (70 dB(A)) when the calculation task was added to the noise exposure [9]. Thus, plasma cyclic AMP which has been advocated as a second messenger of various 599 0022–460X/95/390599+07 $12.00/0
7 1995 Academic Press Limited
600
. ET AL .
hormones by Sutherland et al. [10–12] was a sensitive index for noise-related stress in human subjects. It reflects autonomic nervous functions [13], central nervous functions and hormone secretion resulting from the stimulation of many receptors. In our previous study [14], we used the State-Trait Anxiety Inventory (STAI) developed by Spielberger [15] and investigated the validity and reliability of both these scales, that is A-state and A-trait, and at the same time examined them under various conditions. We have found that noise exposure of over 75 dB(A) plus a calculation task increased A-State scores, but that the individual differences in responses were large. In this study we have examined the effects of noise exposure and/or a calculation task on plasma cyclic AMP concentration and STAI-A-State scores. We used these two indices because they can measure reaction to noise stressors, plasma cyclic AMP being a physiological index and A-State being a psychological index. We examined points of agreement and differences in results obtained by using these indices in the effects of only the calculation task, only noise exposure and noise exposure plus calculation task. The rates of increase in plasma cyclic AMP and changes in A-State scores after noise exposure plus the calculation task as stress indices were examined in relation to their sensitivity and specificity. 2. SUBJECTS AND METHODS
The subjects were 154 female student volunteers, aged 18 to 19 years, with normal hearing ability: 19 subjects were placed in the control group, 28 in the calculation group, 21 in the noise group and 86 in the noise plus calculation group by random selection. On the day of the experiment, they were required to stay in a quiet room from noon onwards (light conversation and reading being permitted). At 3:00 p.m. subjects were taken into a noise laboratory which had a background noise level of less than 40 dB(A), temperature between 23°C and 25°C and humidity between 60% and 80%. The subjects in the noise group were exposed to acoustic stimulation (90 dB(A) pink noise) for 15 minutes, with alternating ON time of 55 s and OFF time of 5 s. The ‘‘pink noise’’ was generated by a Rion Generator (SF-04) and further magnified with an amplifier (SS-02) to 90 dB(A). Pink noise was chosen for this study as it has a frequency characteristic of octave −3 dB, consists of many frequencies and is similar to environmental and industrial noise. The noise exposure level used was 90 dB(A), which is not usual for the general environment but is common in the indusrial environment. Each subject in the calculation and in the noise plus calculation groups was requried to execute 20 multiplication problems each consisting of three figures in 15 minutes. Before and immediately after noise exposure and/or calculation task, blood samples were drawn into test tubes containing EDTA-Na. These samples were centrifuged immediately after collection, and the plasma was frozen and stored at −20°C until assayed. Plasma cyclic AMP was measured by radioimmunoassay, using a YAMASA Cyclic AMP kit. The STAI-A-State also was measured before and after noise exposure and/or calculation task. The STAI-A-State that we used was a questionnaire developed by Spielberger [16] and translated into Japanese by Toyama [17]. We have previously reported the methods for carrying out measurements on this STAI-A-State scale in detail [14]. The questionnaires requested a four-stage reply. On this scale, the larger the score, the higher the anxiety; the total score of the A-State is from 20 to 80 points. The student volunteers in the control group were not subjected to noise exposure and were given no calculation task. The other conditions for the control group were the same as those for the other groups. Plasma cyclic AMP and A-State were measured in the control group as in other groups.
/
601
3. RESULTS
In Table 1 are shown plasma cyclic AMP concentrations, the rates of change in plasma cyclic AMP, the A-State score, and the rates of change in the A-State scores in the control, calculation, noise and noise plus calculation groups. In the calculation group, neither plasma cyclic AMP concentration nor the A-State score showed any significant change compared with pre-task values. In the noise group, the A-State score increased significantly after noise exposure compared with pre-noise exposure values (pQ0·001), while in the noise plus calculation group, both plasma cyclic AMP concentration and A-State score increased significantly compared with pre-exposure values (pQ0·001). In the noise group, the rate of increase in A-State score was significantly (pQ0·001) larger than that in the control group, but the rate of increase in plasma cyclic AMP did not change significantly. The rates of increases in plasma cyclic AMP and A-State score in the combined group were significantly larger than those in the control group (pQ0·001 and pQ0·01). The pre-exposure A-State score in the noise plus calculation group was significantly larger than that in other groups. All subjects in the control group had A-State scores below 42, while some in the noise plus calculation group had more than 42. The ratio of the pre-exposure A-State score to the post-exposure A-State score is statistically significant in the noise and noise plus calculation groups. In Table 2 is shown further classification of the noise plus calculation group based on the pre-exposure A-State score being q42 or E42. The plasma cyclic AMP concentration, the rates of change in the plasma cyclic AMP, the A-State score and the rates of change in the A-State scores are shown. The rate of increase in A-State score in the q42 group was significantly smaller than that in the E42 group (pQ0·01). When comparing the noise plus calculation group with the only noise group, the rate of increase in the A-State score in the E42 group was not significantly different.
T1 Plasma cyclic AMP concentrations and A-State scores in control, calculation, noise and noise plus calculation groups Group ZXXXXXXXXXXXXXXCXXXXXXXXXXXXXXV Noise plus Control Calculation Noise calculation (n=19) (n=28) (n=21) (n=86) (1) c-AMP(pmol/ml) (pre-exposure) (2) c-AMP(pmol/ml) (post-exposure) (3) ((2)−(1)) (4) ((2)/(1)) (5) A-State score (pre-exposure) (6) A-State score (post-exposure) (7) ((6)−(5)) (8) ((6)/(5))
11·1722·04
11·6622·12
11·5821·54
11·8822·27
11·1721·81 NS
11·9021·40 NS
12·1421·50 NS
15·0123·07***
0·0021·05 1·0120·09 33·5825·76
0·2521·74 1·0420·15 35·0727·10
0·5621·42 1·0620·12 34·6225·12
3·1222·95((( 1·2920·29((( 40·5728·74&&
36·1127·31 NS
36·2926·87 NS
48·71210·30***
49·93211·06***
14·10210·64((( 1·4320·36(((
9·36211·47((( 1·2720·33((
2·5326·46 1·0920·21
1·2126·88 1·0620·20
Values are means 2 S.D. ***, pQ0·001 before and after the respective exposure (paired t-test). NS, Not significant before and after the respective exposure (paired t-test). ((( , pQ0·001 to control (Student’s t-test). (( , pQ0·01 to control (Student’s t-test). && , pQ0·01 to A-State scores (pre-exposure) in control, calculation and noise groups (Student’s t-test).
. ET AL .
602
T 2 Plasma cyclic AMP concentrations and A-State scores in noise plus calculation groups Noise plus calculation group ZXXXXXXXXXXXCXXXXXXXXXXXV A-State score A-State score (pre-exposure)E42 (pre-exposure)q42 (n=53) (n=33) (1) (2) (3) (4) (5) (6) (7) (8)
c-AMP (pre-exposure) c-AMP (post-exposure) ((2)−(1)) ((2)/(1)) A-State score (pre-exposure) A-State score (post-exposure) ((6)−(5)) ((6)/(5))
11·7722·39 14·7922·78*** 3·0222·86 1·2920·29 35·0224·58 47·46210·36*** 12·44210·58 1·3720·34
12·0622·09 15·3523·50*** 3·2923·13 1·2920·31((( 49·4825·97((( 53·89211·14* 4·41211·26(( 1·1020·23(((
Values are means 2S.D. ***, pQ0·001 before and after the respective exposure (paired t-test). *, pQ0·05 before and after the respective exposure (paired t-test). ((( , pQ0·001 to (A-State score (pre-exposure)E42) group (Student’s t-test). (( , pQ0·01 to (A-State score (pre-exposure)E42) group (Student’s t-test).
Coefficients of correlation between each examined item for the 86 subjects in the noise plus calculation group are shown in Table 3. In the combined group the rates of increase in plasma cyclic AMP and A-State frequently exceeded the 90% upper confidence interval of the controls. The specificities and sensitivities of the two indices are shown in Table 4. The criteria used in this table were the 90% and 95% upper confidence intervals in the controls. The sensitivity of the rate of increase in plasma cyclic AMP was 67·4% and that of A-State 26·7% when the specificity was about 90%. 4. DISCUSSION
We have reported that plasma cyclic AMP concentration in human subjects increased under noise exposure of over 70 dB(A) plus a claculation task [9]. Human plasma anterior pituitary hormones change only a little in response to the above stressors and therefore this
T 3 Correlation matrix (noise plus calculation group n=86) (1) (1) (2) (3) (4) (5) (6) (7) (8)
c-AMP (pre-exposure) c-AMP (post-exposure) ((2)−(1)) ((2)/(1)) A-State score (pre-exposure) A-State score (post-exposure) ((6)−(5)) ((6)/(5))
**, pQ0·01 (between two indices). *, pQ0·05 (between two indices).
(2)
(3)
(4)
(5)
(6)
(7)
0·42** −0·33** 0·72** −0·45** 0·59** 0·96** 0·06 0·09 0·04 0·01 −0·02 0·00 0·02 0·00 0·35** −0·05 −0·06 −0·02 −0·01 −0·43** 0·70** −0·07 −0·07 −0·04 −0·03 −0·51** 0·59** 0·96**
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T 4 Specificities and sensitivities of the rates of increases in plasma cyclic AMP concentration and A-State score (C group=control group, NC group=noise plus calculation group, C.I.=confidence interval in control group)
Criterion
Specificity C group (n=19)(%)
Sensitivity NC group (n=86)(%)
The rate of increase of plasma cyclic AMP
90% upper C.I. 95% upper C.I.
89·5 94·7
67·4 61·6
The rate of increase of A-state score
90% upper C.I. 95% upper C.I.
89·5 89·5
26·7 24·4
change is not detected. On the other hand, changes in plasma cyclic AMP, which we believed to be a sensitive index to noise plus calculation task, were certainly detectable. We have already reported [14] that anxiety increases after exposure to various noise levels plus calculation task. We measured scores on the A-State scale before and after various noise exposures plus calculation task. The A-State score increased significantly by short-term noise exposure of over 75 dB(A) plus a calculation task. The rate of increase in A-State scores was found to occur in direct proportion to the noise exposure level. In our human subjects, noise of more than 75 dB(A) plus a calculation task caused psychological reactions that were different from those caused by noise of less than 70 dB(A) plus a calculation task. However, in our previous study, we did not discuss the effects of only the calculation task or only the noise exposure in human subjects. In the present study, the effects of the above stressors in human subjects were examined both separately as well as simultaneously. Twenty multiplication problems consisting of three figures each were used to produce the stressful condition in combination with noise exposure. The subjects had to execute these problems in 15 minutes. However, these calculations may not have been stressful because A-state score in the subjects did not increase under calculation task alone. There are several reports on performance effects of noise. Harris [18] reported that random and fixed intermittent sound (from 85 dB(A) to 105 dB(A)) did not affect calculation performance. Edsell [19] has pointed out that although the effects of noise on human behavior have been examined experimentally for over 30 years, these studies have usually considered noise as the only independent variable [20] and that studies of multiple stressors involving noise [20, 21] indicate that the combined effects are sometimes synergistic and sometimes antagonistic and that results are often unpredictable. From short-term exposure studies, Mosskov et al. [22] suggested that even noise exposure below 85 dB(A) increased diastolic pressure and catecholamine excretion. However, Lundberg et al. [23] reported that even under well-controlled conditions the results varied depending on the additional load to which the experimental subjects were exposed. Lamp [24] reported that for tasks in which voice communication was unnecessary, the effects of noise on performance appear to depend on the characteristics of the noise, the type of task, and the attitude and personality of the worker, and that the general conclusions usually were as follows: steady state noise under 90 dB(A) does not seem to interfere with work performance. Above 90 dB(A), the results are inconsistent. In a community-based cross-sectional study, Lercher [25] suggested that the public health impact of noisy working conditions, aside from hearing loss, can be underestimated when combined effects were not adequately considered.
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. ET AL .
In this study we did not find any difference in the psychological effects induced by 90 dB(A) noise exposure alone and noise plus the calculation task, but the physiological response to the calculation task performed in presence of noise exposure was significantly larger than that due to the noise exposure alone. The present data show that a physiological effect in human subjects under noise exposure can become larger when a psychological stress (calculation task) is added. The pre-exposure A-State score in the noise plus calculation group was larger than that in the noise group. The subjects in this group may have anticipated a stress situation after discussions with their friends who had done the test. Compared to the control group, the rate of increase in the A-State score in the noise group was larger (pQ0·001) than that in the noise plus calculation group (pQ0·01). Sensitivity and specificity in screening tests have been defined by Thamer [26]. These are also used for the determination of the efficacy of screening by medical examination. The normal value is important in determining the efficacy of screening. The normal range is expressed by using the mean value and the standard deviation for healthy persons. In our results, we found that the sensitivity of the rate of increase in plasma cyclic AMP was larger than that of the rate of increase in the A-State score in the noise plus calculation group. In this group the rate of increase in plasma cyclic AMP exceeded the 90% upper confidence interval in the control group in 67%, and the rate of increase in A-State in 27%. The coefficient of correlation between the rates of increases in the A-state score and the plasma cyclic AMP was not significant. The agreement of physiological reaction and psychological reaction to the noise exposure under mental stress was low. We used two types of tests which gave rather similar results, but the intercorrelation was not good. This could mean that certain individuals reacted in the psychological test and others in the physiological test. This would appear to depend on the personality of the subjects. REFERENCES 1. R. I. H and K. M. K 1963 American Journal of Physiology 204, 710–714. Effect of sound on the hypothalamic–pituitary–adrenal axis. 2. H. A, M. I and Y. T 1976 Journal of the Aichi Medical University Association 4(1), 1–5. Hypothalamo-hypophyseal-adrenal response to noise (threshold limit value for white noise). 3. A. A, N. W. B and G. J. C 1979 Journal of Histochemistry and Cytochemistry 27(10), 1380–1381. Cytochemical bioassay and radioimmunoassay of ACTH in noise stressed rats. 4. A. E. A, D. I, J. P. O and M. C 1962 Journal of Clinical Endocrinology and Metabolism 22, 846–852. Pituitary-adrenal stimulation by sound of different frequencies. 5. G. B, M. F and C. T 1977 European Journal of Applied Physiology 36, 239–246. Failure of noise exposure to modify temporal patterns of plasma cortisol in man. 6. G. B, M. F, G. W and P. S 1980 Biological Psychology 10, 239–252. Plasma catecholamines and pituitary adrenal hormones related to mental task demand under quiet and noise conditions. 7. A. F, A. T, L. B, A. M, C. A and G. P 1975 Medicina del Lavoro 66(2), 109–118. ACTH and corticoids levels in plasma with contemporaneous EEG changes during noise in man. 8. L. A, G. L, M. B, K. O. B and L. H 1982 Clinical Science 62, 137–141. Effect of noise on blood pressure and stress hormones. 9. M. I, H. D, F. I, J. Y, S. Y and H. G 1988 Journal of Sound and Vibration 127, 431–439. The plasma cyclic-AMP response to noise in human and rats (short-term exposure of various noise levels). 10. E. W. S and T. W. R 1960 Pharmacological Reviews 12, 265–299. The relation of adenosine-3',5'-phosphate and phosphorylase to the actions of catecholamines and other hormones.
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