If we want to provide the efficient training intervention to increase
the duration of using hearing protection devices (HPDs) by workers, we
need a tool that can estimate the person’s hearing threshold taking into
account noise exposure level, age, and work history, and compare them
with audiometry to find out the percent reduction of workers hearing
First, the workers noise exposure level was determined according to ISO
9612, then 4000 Hz audiometry was done to find age and work history. On
basis of ISO 1999 the hearing threshold was estimated and if the hearing
protection device was not used continuously and correctly, the hearing
protection device’s actual performance was reduced adjusted with
person’s audiometry. After training intervention, the estimate was done
again and was compared with the adjusted audiometry.
According to ISO 1999 standard estimation results, the percent reduction
of the workers hearing loss level was 6.48 dB in intervention group.
This level remained unchanged in control group. The mean score of
hearing threshold estimation (standard ISO 1999) was statistically more
significant than mean score of hearing threshold (p-value ¡ 0.001). The
results show not significant change in control group due to lack of
changing of noise exposure level.
In regards to the results of hearing threshold estimation based on ISO
1999 and comparing with workers audiometry, it can be seen that BASNEF
training intervention increases the duration of using the HPDs and it
could be effective in reducing hearing threshold related to noise.