Evaluation of cognitive function after exposure to different levels of sound pressure levels in the clinical trial study. Is 65 dB level safe?

In addition to the adverse effects of noise in the auditory system, non-auditory effects can be regarded as factors which cause physiological harassment, discomfort and also disorder in cognitive functions. The present study aimed at determining cognitive function after exposuring to different levels of sound pressure level in a clinical trial study.
This study was clinical trial type (before and after clinical trial). In order to evaluate the effects of noise (65, 75 and 85 dB) on cognitive function, 12 students (6 males and 6 females) of Isfahan Medical Science University students between the ages 22 and 27 with BMI 20-25kg/m were studied. To analyze data, the statistical pair-T test was used and ANOVA (P=0.05) was run.
Applying sound pressure level of 65 dB in comparison with prior applying of 65 dB sound pressure level led to average increase in chosen reaction times colors (P=0.041) and sounds (P=0.038) were significant. Also, by increasing the sound pressure level of 65 dB to 75 and then 85 dB reaction time average increase was significant (001/0> P).
Accordingly, the 75 and 85 dB sound pressure level of 65 dB sound pressure range cannot be considered within safe limits for non-auditory effects according to its impact on cognitive function. Besides, this issue in jobs that expose people to high sound leads to disorder in cognitive function (reaction time, attention, etc.) causing the risk which must be taken into consideration.