Maternal occupational noise exposure during pregnancy and children's early language acquisition.

INTRODUCTION: Noise exposure during pregnancy may affect a child's auditory system, which may disturb fetal learning and language development. We examined the impact of occupational noise exposure during pregnancy on children's language acquisition at the age of one. METHODS: A cohort study was conducted among women working in the food industry, as kindergarten teachers, musicians, dental nurses, or pharmacists who had a child aged <1 year. The analyses covered 408 mother-child pairs. Language acquisition was measured using the Infant-Toddler Checklist. An occupational hygienist assessed noise exposure individually as no (N = 180), low (70-78 dB; N = 108) or moderate/high exposure (>79 dB; N = 120). RESULTS: Among the boys, the adjusted mean differences in language acquisition scores were -0.4 (95% CI -2.5, 1.8) for low, and -0.7 (95% CI -2.9, 1.4) for moderate/high exposure compared to no exposure. Among the girls the respective scores were +0.1 (95% CI -2.2, 2.5) and -0.1 (95% CI -2.3, 2.2). Among the children of kindergarten teachers, who were mainly exposed to human noise, low or moderate exposure was associated with lower language acquisition scores. The adjusted mean differences were -3.8 (95% CI -7.2, -0.4) for low and -4.9 (95% CI -8.6, -1.2) for moderate exposure. CONCLUSIONS: In general, we did not detect an association between maternal noise exposure and children's language acquisition among one-year-old children. However, the children of kindergarten teachers exposed to human noise had lower language acquisition scores than the children of the non-exposed participants. These suggestive findings merit further investigation by level and type of exposure.

Vocal loading among day care center teachers.

Day care center teachers suffer from voice disorders more often than nurses do. Several risk factors may increase voice disorder prevalence of day care center teachers. The risk factors can be bound to their job content and manner of working i.e. having to raise their voice to attract the attention of the children and to offer them the possibility to perceive spoken information, or to the environment i.e. poor acoustics and excess background noise. The purpose of this study was to measure some of the risk factors for voice disorders of day care center teachers and of a control group (nurses); these were speaking times and speech levels. The background noise levels during activities and RASTI-values (Rapid Speech Transmission Index), i.e. measures of the acoustics of rooms, were also measured at the day care centers. It was found that day care center teachers use their voices more and with higher levels than nurses do. It was also found that the background noise levels are high, which is partly due to the poor acoustics (lack of sufficient attenuation) of the rooms. Control of excess background noise is of utmost importance both for speakers' speech production as well as children's speech recognition.