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 self-rated disturbance in individuals with HI than low-level noise.
Purpose: The purpose of this study was 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 in four experimental
conditions.
Study Sample: A total of 40 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 using 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 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 4 wk of each
other. All tasks and experimental conditions were used in a counterbalanced order.
Two-way analysis of variance with repeated measures was performed to analyze the results.
To examine interaction effects, pairwise t -tests were used. Pearson correlation coefficients between reaction time 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-group 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 demonstrated that the group with HI was more disturbed
by higher than lower levels of noise (i.e., traffic and daycare setting compared with
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
settings compared with office noise.
Conclusions: The present results demonstrate that background noise does not impair cognitive performance
in nonauditory tasks in employees with HI and normal hearing, but that PD is affected
to a greater extent in employees with HI during higher levels of background noise
exposure. In addition, this study also supports previous studies regarding the detrimental
effects that high-level noise has on employees with HI. Therefore, we 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.
Key Words Cognitive performance - labor market - hearing impairment - noise - perceived disturbance
- work
