Background: Health care professionals frequently meet employees with hearing impairment (HI) who experience difficulties at work. There are indications that the majority of these difficulties might be related to the presence of background noise. Moreover, research has also shown that high level noise has a more detrimental effect on cognitive performance and selfrated disturbance in individuals with HI than low level noise.
Purpose: To examine the impact of different types of background noise on cognitive performance and perceived disturbance (PD) in employees with aided HI and normal hearing.
Research Design: A mixed factorial design was conducted to examine the effect of noise under four experimental conditions.
Study Sample: Forty participants (21 men and 19 women) were recruited to take part in the study .The study sample consisted of employees with HI (n =20) and normal hearing (n = 20). The group with HI had a mild-moderate sensorineural HI and they were all frequent hearing aid users.
Intervention: The current study was conducted by employing four general work-related tasks (mental arithmetic, orthographic decoding, phonological decoding and serial recall) in four different background conditions: (1) quiet, (2) office noise at 56 dBA, (3) daycare noise at 73.5 dBA and (4) traffic noise at 72.5 dBA. Reaction time (RT) and the proportion of correct answers in the working tasks were used as outcome measures of cognitive performance. The Borg CR-10 scale was used to assess PD.
Data Collection and Analysis: Data collection occurred on two separate sessions, completed within four weeks of each other. All tasks and experimental conditions were employed in a counterbalanced order. Two-way analysis of variance (ANOVA) was performed to analyze the results. To examine interaction effects, pairwise t-tests were used. Pearson’s correlation coefficients between RT and proportion of correct answers, and cognitive performance and PD were also calculated to examine the possible correlation between the different variables.
Results: No significant between or within-group differences in cognitive performance were observed across the four background conditions. Ratings of PD showed that both groups rated PD according to noise level, where higher noise level generated a higher PD. The present findings also demonstrate that the group with HI was more disturbed by higher than lower levels of noise (i.e. traffic and daycare setting compared to the office setting). This pattern was observed consistently throughout four working tasks where the group with HI reported a significantly greater PD in the daycare and traffic setting compared to the office noise.
Conclusions: The present results demonstrate that background noise does not impair cognitive performance in non-auditory tasks in employees with HI and normal hearing, but that PD is affected to a greater extent in employees with HI during higher level of background noise exposure. In addition, this study also supports previous studies regarding the detrimental effects high level noise has on employees with HI. We therefore emphasize the need of both self-rated and cognitive measurements in hearing care and occupational health services for both employees with normal hearing and HI.
American Academy of Audiology , 2014. Vol. 25, no 9, 859-868 p.
Cognitive performance: labor market; hearing impairment; noise; perceived disturbance; work