A new study reveals that while three-quarters of factory workers report they have good hearing, nearly half actually had compromised hearing. Researchers at the University of Michigan School of Nursing studied 2,691 workers at a Midwest automobile factory, where 76 percent reported their hearing as "excellent" or "good." According to the study results, however, 42 percent of noise-exposed workers had hearing loss.
The study led researchers to conclude that self-reported hearing loss was poorly related to the results of audiometry, and stressed "a need for development of reliable and valid self-report measures of hearing ability."
The study cites NIOSH data that estimates 5.7 million manufacturing workers are exposed to hazardous occupational noise. This represents a quarter of all American workers exposed to noise on the job.
"Workers in this study sample were protected by a workplace hearing conservation program in compliance with the OSHA Hearing Conservation Amendment designed to protect noise- exposed workers from the negative effects of their exposure. However, despite this protection, results of this analysis were sobering," the study stated. "Although the results cannot determine the sources of their hearing loss (i.e., work-related, other environmental exposures, biologic, chemical, and pharmacologic factors), these findings demonstrate the need for continued policy and program development to protect workers' hearing, even in regulated industries."
The study participants were exposed to 80 or greater decibels (A-weighted, 8-hour TWA) of noise at work. They self-reported their hearing ability by rating their hearing as excellent, good, fair or poor. Researchers then studied their audiograms to determine whether hearing loss was present.
Older white males who worked longer at the plant and who reported lower rates of high school graduation and lower use of hearing protection reported more hearing loss than those without hearing loss. Overall, the participating workers reported using hearing protection only 69 to 80 percent of the time they were exposed to high noise.
According to Dr. Marjorie McCullagh, assistant professor and lead study author, the study results show that workers may be unaware of their actual hearing ability, even if they are served by a workplace hearing conservation program and receive annual hearing testing.
"Consequently, health care providers would be wise to examine methods to help workers develop more accurate perceptions of their hearing, and test more effective methods to protect it," she said.
The study authors identified a need for surveillance methods, policies and programs that address the hearing protection needs of workers to help evaluate the effectiveness of hearing conservation programs, identify hearing health concerns and prevent occupational hearing loss.