A scale of vibration greatness (VG) corresponding to loudness (sone) in psycho-acoustics was determined on the whole body and hand vibrations in vertical and hor-izontal directions. This scale has true ratio properties, and numbers on this scale having a given ratio refer to vibrations whose sensation has that ratio. The corrected ratio method devised by W. R. Garner for loudness measurement was used in our ex-periment. This method consists of two experiments which are based on fractionation and equisection judgments. The unit value of VG was decided as 40 VGL (1 VG=40 VGL). Vibration greatness level (VGL) corresponds to loudness level (phon) as defined in Part 1. The experiments were carried out mainly at 20c/s. The effect of frequency on vibration greatness was examined at 5, 30 and 60 c/s. The vibration greatness for both of whole body and hand can be shown by following two equations. log VG = 0. 030 VGL-1.20, below 1 VG. log VG = 0. 023 VGL-0.92, above 1 VG. Dependency on frequency was not observed.
The vibration greatness levels of the artificial compound vibrations composed of several sinusoidal vibrations at the center frequencies of the octave bands between 1 and 250 c/s were measured by comparison with the standard frequency vibration of 20 c/s. Combinations of amplitudes, frequencies and numbers of their components were changed variously. The level of the standard vibration was varied by the tester by the same procedure as in the measurement of the vibration greatness level. Conversion of observed VGL values to VG ones was made by the equation (4) described in Part 4. Effects of frequency intervals, levels and numbers of components in compound vibrations on vibration greatness were examined. On the whole body and hand vibrations in vertical and horizontal directions total vibration greatness (VGT) could be estimated from each VG value of components (VGi) and the maximum value (VGM) by using equation proposed by S. S. Stevens, VGT=VGM + 0.3((∑ VGi) - VGM).
To obtain human emotional response such as unpleasant and intolerable for sinu-soidal vibrations in the short-time exposure within 10 min, ten male subjects were vibrated from low to high levels at 6 grades (difference of each grade; 5 dB) during 3 min for each. The subjects were requested to describe the emotional judgment to the given vibration at each step, unpleasant or intolerable or not. These results were plotted on an ogive by each frequency, and tolerance limit and unpleasant levels were defined at 50% point on them. The frequency characteristics of the emotional response for the whole body vibrations in vertical and horizontal directions and for the hand vibrations were almost similar to Fig. 13 in Part 1 and Fig. 5 in Part 3 respectively. This tendency did not vary in the range of the exposure time between 1 and 10 min. Moreover, on the whole body and the hand vibrations, an estimation equation for the criterion of long exposure time was also discussed.
Vibration and coldness are the causes producing the lesions due to vibratory tool work. This paper describes the results obtained from measurements of the vibration acceleration of rock drills under the various conditions and the results obtained from measurements of air temperatures at 35 pits in a certain metal mine. The rock drills had remarkably great vibration : according to the author's measure-ments, the greatest vibration was found in the sinker-type drill, the second in the stopper and the third in the leg-type drill with or without vibration-proof handle. The vibration of the drill in digging the hard rock was greater than that in digging the soft rock. The vibration in the initial cutting was less than that in the drilling operation. Measurements of the vibration acceleration transmitted to the body when the drill was used revealed that both hands were exposed to the vibration of almost similar intensity, and the vibration transmitted to the body tended to decrease gradually from the hand to the central region. The measurements of air temperatures at 35 pits which were selected at random in this mine were made on February, April, April, May, August, October and December. The mean temperature was 13.5 ± 2.4°C in August, while 6.0 ± 3.7°C in February. In summer there was little difference among the temperatures of pits but in winter a little.
Raynaud's phenomenon occurs due to vibratory tool work. The studies on the diagnosis have long been made, but much yet remains unclear. This paper describes the results of inquiry concerning blanching and numbness of fingers and also the results obtained from the examination on the Raynaud's phenomenon. These studies were carried out on 529 persons in a certain metal mine. The occurrence rate of Raynaud's phenomenon (complaints of the blanching of fingers or the numbness of fingers) was about 52%. It had not a clear correlation with age, vibratory work experience and period up to the first appearance of these symptoms. Miners complained of the symptoms at the highest rate, and was followed by putters, propsetters and miscellaneous underground workmen. Raynaud's phenomenon occurred in relation with the operating hour with rock drill per day, appeared on the 2 nd, 3rd and 4th fingers frequently regardless of the hand which operated the drill, and occurred all the year round without relation with season. According to the results obtained from the examination, it was observed that patients of Raynaud's phenomenon showed low skin temperature during immersion of the hand in cold water (5°C) and that the lower the skin temperature, the more severe the symptoms. The sensitivity of two-point sensibility and of pain at the finger-tip had statistically significant difference between the patient group and the healthy subjects, after immersion in cold water. Capillary views at the nail bed indicated that some patients showed abnormal loops and others normal. Finger-plethysmograph indicated the same tendency. Reactive hyperemia time in the patient group was longer than that in the healthy group.
Vibration causes the injury to bones and joints. This paper describes the results obtained from the survey of the subjective symptoms of joint pain and muscle pain, the findings of radiographic observation of the views at the wrist, the elbow, the shoulder and the cervical vertebrae and the findings of the elbow joint views related to the grasping power. The studies were carried out on the underground workmen in a certain metal mine. The occurrence rates of complaints of joint pains and muscle pains were 46.9 and 36.7% respectively. The muscle pain had no relation with age and vibratory work experience, but the joint pain had some. These complaints had no relation with the period up to the first appearance. No marked difference of complaints was found among the groups of workmen by operation. However, they had the relation with the operating hour with rock drill per day. The joint pain appeared in the elbow most frequently, followed by the wrist. The muscle pain appeared in the forearm and the upper arm of the side of the hand operating the tools. While the wrist, the shoulder and the cervical vertebra did not show the remarkable deformity, the elbow showed the remarkable deformity especially at the coronoid process and the articular surfaces. A parallel relationship was not obtained between the sub-jective elbow pain and the roentgenographic abnormal findings. Workers whose grasping power was weak showed remarkable abnormal findings of elbow joint.
Experiments were performed to determine the effectiveness of signal rates on phy-siological functions and detection performance during a visual vigilance task. Experi-ment I employed a rate of 183 signals/ hr ; experiment II employed a rate of 35/hr. Subjects were 10 male college students and they watched the clock panel and responded to the signals by pressing a key during 2 hours. Same subject performed the task on the two experimental conditions. It was found that the initial increase of galvanic skin reflex (GSR) frequency could be seen at the start of the task, whereas the changes of respiratory rate, heart rate and amplitude of rhythmic fluctuation of blood volume did not occur. It was also found that respiratory rate, amplitude of waves and GSR frequency showed approximately the same value in both experiments, except that the heart rate in experiment I was higher than that in experiment II. It was interesting that the subjects reported that experiment I was easily performed as compared with experiment II, though experiment I seemed to be harder than experiment II from the viewpoint of the heart rate. The detection performance in experiment I was generally similar to that in experi-ment II. Clear relationship between the variations in these physiological functions and detection performance with time course could not be found, nor did unique changes of the instantaneous physiological responses corresponding the cases of missing and pushing the key in absence of signal occur.
The cell toxicity and hemolytic action of asbestos dusts were studied. The toxic effect of asbestos dusts to macrophages was estimated by the change of acid phosphatase activity, TTC reducing capacity and lactic acid yielding power of the cells. The rise of acid phosphatase activity, drop of lactic acid production and hemolysis were provoked by sepiolite, palygorskite and chrysotile among asbestos dusts. But, the drop of TTC reducing capacity was not clearly produced by these asbestos dusts. The other asbestos dusts were inert on the macrophage and erythrocyte. Furthermore, intraperitoneal injection of sepiolite was very harmful to rat. That is, all injected rats died within 48 hours, while there was no lethal case in injected rats with antigorite and their weights followed the curve of non-injected rats for 3 months.
Effects of sulphur dioxide gas, mists of aqueous sulphur dioxide and of sulphuricacid solution and silica gel particles exposed to sulphur dioxide and to sulphuric acid solution on the metal film were studied electronmicroscopically. Mists of aqueous solution of sulphur dioxide and sulphuric acid showed very similar but a little different figures. Sulphur dioxide and particles, absorbing sulphur dioxide or sulphuric acid, showed a corrosive effect on the metals with or after the exposure to high humidity. It was emphasized that the biological effects of these pollutants should be consideredtogether with air humidity.