Subject recruitment
At each site, volunteers were recruited among noise-exposed workers with the only eligibility criterion being current enrollment in
the company hearing conservation program. Recruitment took place through distribution of educational materials about the study
and in person meetings between groups of workers and the investigators. Company management did not take part in subject recruitment sessions, and volunteers provided written informed consent under study protocols approved by the Yale Human Investigation Committee. There was no exclusion of individuals with preexisting hearing loss or other medical conditions. After providing consent, workers were fitted with noise monitoring devices consisting of a dosimeter that is carried in a pocket or worn on a belt or hard hat (Figure 1) and connected by wires to small microphones (one for the left ear and one for the right ear) that record noise exposure under hearing protection devices. Dosimeter settings are similar to those used for OSHA hearing conservation compliance (5-dB exchange rate, slow response, 80-dBA noise floor). Study volunteers were asked to use these dosimeters on a daily basis as part of their regular hearing protection and to download the noise exposure data from the dosimeter at the end of each work shift. The data are downloaded to a computer database using an infrared reader connected to a computer workstation located near the shop floor. At the time of download, the computer displays the worker ’ s cumulative noise exposure ( ‘ dose ’ ) for the work shift, expressed as a percentage of the OSHA permissible exposure level (90 dBA for 8 hour TWA). This exposure information is confidentially transferred to the research team, and monthly summaries of exposures are sent to the study volunteers. Volunteers were advised to attempt to keep daily noise doses below the 50% dose level (85 dBA for 8 hour TWA), which is the OSHA action level and the Alcoa corporate occupational exposure limit level. The dosimeter comes equipped with visual warning signals to alert workers to their exposures while wearing the device. LEDs on the device turn yellow when the daily cumulative dose exceeds 45% dose (84 dBA), flashes red when short-term exposures are over 85 dBA, and remains a constant red when daily cumulative dose exceeds 100% (90 dBA, 8 hour TWA). In addition to performing daily noise exposure monitoring, volunteers were asked to complete a baseline questionnaire of demographic information and risk factors for hearing loss, including non-occupational noise exposures. An annual questionnaire was sent to volunteers to obtain updated information about their health and hearing status, as well as information about the usability of the device. Focus groups were also conducted to address the usability of the device.
เรื่องรับสมัครที่แต่ละไซต์ อาสาสมัครได้รับในหมู่ผู้ปฏิบัติงานสัมผัสเสียงดัง มีเกณฑ์คุณสมบัติเฉพาะที่มีการลงทะเบียนปัจจุบันในโปรแกรมการอนุรักษ์การได้ยินบริษัท สรรหาบุคลากรเกิดขึ้น โดยการแจกจ่ายวัสดุการศึกษาเกี่ยวกับการศึกษาand in person meetings between groups of workers and the investigators. Company management did not take part in subject recruitment sessions, and volunteers provided written informed consent under study protocols approved by the Yale Human Investigation Committee. There was no exclusion of individuals with preexisting hearing loss or other medical conditions. After providing consent, workers were fitted with noise monitoring devices consisting of a dosimeter that is carried in a pocket or worn on a belt or hard hat (Figure 1) and connected by wires to small microphones (one for the left ear and one for the right ear) that record noise exposure under hearing protection devices. Dosimeter settings are similar to those used for OSHA hearing conservation compliance (5-dB exchange rate, slow response, 80-dBA noise floor). Study volunteers were asked to use these dosimeters on a daily basis as part of their regular hearing protection and to download the noise exposure data from the dosimeter at the end of each work shift. The data are downloaded to a computer database using an infrared reader connected to a computer workstation located near the shop floor. At the time of download, the computer displays the worker ’ s cumulative noise exposure ( ‘ dose ’ ) for the work shift, expressed as a percentage of the OSHA permissible exposure level (90 dBA for 8 hour TWA). This exposure information is confidentially transferred to the research team, and monthly summaries of exposures are sent to the study volunteers. Volunteers were advised to attempt to keep daily noise doses below the 50% dose level (85 dBA for 8 hour TWA), which is the OSHA action level and the Alcoa corporate occupational exposure limit level. The dosimeter comes equipped with visual warning signals to alert workers to their exposures while wearing the device. LEDs on the device turn yellow when the daily cumulative dose exceeds 45% dose (84 dBA), flashes red when short-term exposures are over 85 dBA, and remains a constant red when daily cumulative dose exceeds 100% (90 dBA, 8 hour TWA). In addition to performing daily noise exposure monitoring, volunteers were asked to complete a baseline questionnaire of demographic information and risk factors for hearing loss, including non-occupational noise exposures. An annual questionnaire was sent to volunteers to obtain updated information about their health and hearing status, as well as information about the usability of the device. Focus groups were also conducted to address the usability of the device.
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