·Industrial physicians·Industrial nurses·Health managers·WorkerStep 4Attached horizontallyStep 1Step 2Attached verticallyStep 3Examples for how to wear the noise dosimeterTo measure noise exposure correctly, the NB-14 must be worn on the shoulders, neck, or head within the hearing zone (defined as the area within 30 cm of the ears). When worn on the shoulder, it may be attached either horizontally or vertically using a crocodile clip to secure it in place.Workplace proceduresTo the left is an image of the workplace environment assumed in accordance the Guidelines for the Prevention of Noise-Induced Impairments (Revised). To protect worker hearing, the business operator and a medical institution are required to gather data and submit a report on personal noise exposure measured using the NB-14. The industrial physicians, industrial nurses, and health managers then distribute hearing protection equipment, such as earplugs, based on the information provided.Hearing zone30 cmradius“We visited workplace environments at railroad companies, motorcycle man-ufacturers, and steel mills and talked to the people who worked at the sites,” recounts Takeshi Nakaichi. “We also had repeated discussions with organizations specializing in measurement and with experts in occupational health at the University of Occupational and Environ-mental Health in Kitakyushu City. Based on these discussions, we came to the con-clusion that people wanted noise dosime-ters that were light and compact, with low power consumption, which could be worn securely without falling off. The on-site workers had to wear the noise dosimeters on their person during their entire shift, so the device couldn’t get in the way of their work, which sometimes involves significant motion. So the bold decision was made to eliminate the dis-play screen from the device. This resulted in significant reductions in weight, size, and energy consumption. But a screen for checking noise levels is considered to be a standard feature of noise dosimeters. Up to the very end, some persisted in their doubts: There’s no way to make a decent meter without a screen…”Another issue was that the micro-phone would sense the shock of the unit being dropped or being struck by some-thing as a loud noise, which the dosime-ter would erroneously include in the measurements. This problem was solved by Daisuke Yamashita, a member of the Noise Dosimeter Development Project.“We repeated tests to determine the extent to which the device could correct-ly detect a drop or a shock, then using threshold values obtained and an embed-ded sensor, developed a dosimeter that can distinguish between environmental noise and sounds created by impact.”Various methods were examined to keep the device from falling off. A croco-dile clip attached to the unit secures the device in place. Even during work involv-ing vigorous motion, the device will not fall off. The development team continues its efforts to design a unit that can be attached to helmets as well, rather than just on the worker’s shoulder.In addition to pursuing comfort for those wearing the device, the team has streamlined the functions and focused on convenience in order to achieve a lighter and smaller design. Only a single button is used for the power on/off or measurement start/stop. The measure-ment results are saved automatically inside the NB-14. AS-05, the data man-agement software, allows users not just to view measurement data, but also to pre-pare a report in accordance with a report template specified under the revised guidelines. This one-stop process for both measuring and reporting frees organizations from unnecessary labour and enables them to devote more time to implementing actual measures to prevent noise-induced hearing loss.The goal that lies aheadWhile the engineers were struggling through trial and error to develop the hardware for a noise dosimeter, which was completely different from a sound level meter, Takeshi Nakaichi and Aoi Takeda of the Project for Preventing Noise-induced Hearing Loss were work-ing hard to strengthen the presence of Rion in the occupational health market, a new area for the company, and to pro-mote the effectiveness of the NB-14. Using a prototype NB-14, they per-formed investigations at numerous noisy workplaces and at working environment measurement agencies, including inves-tigations carried out at metal processing workplaces and clean rooms. They also participated actively in meetings of the Japan Occupational Hygiene Association and the Society of Occupational Hearing Loss to present their research results. Takeda, who worked with Nakaichi, recalls feeling the positive response from the audience.“Our presentation focused on how to use the noise dosimeters and how to wear them for more accurate measurements. Takeshi NakaichiNew Market Development Group, R&D Depart-ment of the Technical Development Center. Having joined Rion in 1995, he is the key individual behind development of the NB-14, the first domestic noise dosimeter. As a leader of the Project for Preventing Noise-induced Hearing Loss, he has contributed to raising Rion’s profile in the occupational health industry and to spreading awareness of the ef-fectiveness of the NB-14.Give orders for measurements.Measure.Submit a report.Collect data.Instruct workers to wear selected protective equipment.Confirm the effectiveness of the equipment and provide feedback.·Work environment monitoring expert·MeasurerCollecting measurement dataPreparing a reportImplementing riskmitigation measuresConfirming the effectivenessof such measures4
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