[A trial measurement of individual noise exposure by time-zone in a day (author's transl)].

Noise has been measured usually for a particular source or place and not for each individual exposed. It has been thought to be of great significance if individual noise exposure is recorded in various kinds of noise environment and auditory effects of noise on each individual can be discussed. The present study, having each of examinees carry 10-Channel Noise Exposure Meter with him, intended to know about dose or equivalent sound level (Leq) of individual nois exposure for a whole day and for each of eight time-zones in a day. The examinees were 12 male married workers in a factory manufacturing electronic machines in Kawasaki City, Kanagawa Prefecture, Japan. They were divided into two groups; those who were working in a noisy workshop (Group N, 8 workers) and those who were working in a less noisy workshop (Group N-N 4 workers). Time-zones were categorized as follows: (a) time from rising to leaving home for the place of work, (b) commuting time in the forenoon, (c) working time in the forenoon, (d) noon recess time, (e) working time in the afternoon, (f) commuting time in the afternoon, (g) time from returning home to going to bed, and (h) sleeping time. Leq (c) and Leq (b) were highest and Leq (h) was lowest for Group N among the eight Leq values in the day, while Leq (b) and Leq (f) were highest for Group N-N. Statistically significant differences of Leq for each time-zone between the two groups were found in Leq (c), Leq (d) and Leq (e), whose energy average sound levels for Group N and Group N-N were 84.2 and 59.4 dB, 72.7 and 61.4 dB, and 85.5 and 61.4 dBrespectively. Energy average equivalent sound levels of Leq (24) were 81.0 dB for Group N and 66.7 dB for Group N-N. Leq (24) for Group N were primarily determined by the noise exposure in the working time (c and e), while those for Group N-N by that in the commuting time (b and f). Practical disadvantages in the course of individual application of 10-Channel Noise Exposure Meter were also pointed out. It was shown that it is possible individually to measure the noise exposure dose for each time-zone in a day or daily noise exposure pattern, and the noise exposure dose over 24-hour. It may be recommended that many typical noise exposure patterns and 24-hour noise exposure doses for each of the groups classified by sex, age, kind of job, kind of commuting methods, kind of residential area of residential area and so forth should be surveyed further, which will be useful for estimating the auditory effects of noise on a population. Also, the relationships between Leq and such effects as annoyance or interference with daily activities should be examined to ease the measurement of noise.