Noise is the most common cause of reported workplace injuries in the EU. Research in the field has focused on high-risk industrial environments. Female-dominated workplaces, which are often communication-intense, have been largely ignored. Among them are obstetric wards, in which sound levels especially during childbirth are difficult to control and potentially hazardous.
Researchers at Sahlgrenska Academy, University of Gothenburg, have studied occupational noise exposure at one of the largest Swedish obstetric wards. Published in the BMJ Open online journal, the study found that daily exposure during almost half of the shifts exceeded the lower action level 80 dB LAeq set for protection of hearing (see fact box).
Delivery under way
Also the upper exposure action level (daily exposure limit 85 dB LAeq) was exceeded during 5% of the shifts, whereas 115 dB LAFmax, the upper short-term limit set by the Swedish Work Environment Authority, a level comparable to peak levels at rock concerts, was occasionally exceeded as well.
“We recorded 50 events during 61 shifts during which 115 dB LAFmax was exceeded,” says Sofie Fredriksson, researcher at Sahlgrenska Academy. “Activity logs enabled us to link six of the occasions to a delivery that was under way at the time.”
A total of 55% of obstetrics personnel experienced some type of hearing-related symptoms.
“Sound-induced auditory fatigue and difficulty perceiving speech, which was reported by one-third of the personnel, were the most common symptoms,” Ms. Fredriksson says. “We also found a significant association between calculated noise exposure dose, tinnitus and sound-induced auditory fatigue. Previously auditory fatigue had been observed among teachers, who say that they cannot handle ordinary noise after a typical workday. While additional research is need to understand the mechanisms and health effects of auditory fatigue, our studies suggest that it should be regarded as a serious sign of a hazardous sound environment for healthcare professionals as well.”
Hearing protection devices may be difficult for obstetrics personnel to wear. Those who participated in the study had come up with homemade solutions of their own: one would ask women to scream into the the nitrous oxide mask while another encouraged them to concentrate on bearing down.
“Some of the participants were relieved when we recommended earplugs,” Ms. Fredriksson says. “We recommend those that muffle noise just enough to eliminate the hazardous effects without hampering communication or alienating others.”
Four out of every ten participants experienced a great deal of work-related stress The researchers believe that the sound environment can exacerbate or mitigate stress.
“Appropriate interventions can make for a healthier and more pleasant workplace,” Ms. Fredriksson says. “Some interventions that would be worthwhile trying are offering silent spaces between deliveries, reviewing the sound environment in administrative areas, setting aside rooms for discussions and the completion of medical records, and encouraging personnel to take breaks in peaceful and relaxing settings.”
”The effect of occupational noise exposure on tinnitus and sound fatigue among obstetrics personnel” has been published in BMJ Open.
Link to article: http://bmjopen.bmj.com/content/5/3/e005793.full
dB LAeq corresponds to the average sound level measured with a filter for an extended period of time (ordinarily 8 hours when assessing the work environment) as a reflection of the ear’s sensitivity to various frequencies.
dB LAFmax is the sound level measured for 125 milliseconds with a filter, reflecting the ear’s ability to perceive the full volume of sudden noise.
If you have any questions, feel free to contact:
Sofie Fredriksson, Licensed Audiologist and PhD Student, Sahlgrenska Academy, University of Gothenburg
Office: +46-31-786 36 10