[ impact of low frequency noise on mental performance during math calculations]

The influences of Low Frequency Noise [LFN] on mental performance have been the objectives of many papers in recent years. Many researchers believe that the LFN even at low pressure levels has impacts on mental performance. In the present work the influences of LFN and Reference Noise [RN] at two different sound pressure levels [45 and 65 dBA] on mental performances of college students during solving math problems were studied. Other factors such as annoyance and sensitivity to LFN and hearing status of the participants were also determined. Low Frequency and Reference Noise were generated and verified using cool Edit software program. The number of participants was calculated using data gathered from a pilot study conducted in advance. The mental performance of the students was evaluated while they were exposed to LFN and RN at 45 and 65 dBA sound pressure levels. For this purpose, standard psychological tests were applied. Standard measuring instrumentation including sound level meters, psychological tests, acoustic room and etc were calibrated prior to their application based on standard methods. The results revealed that, Low frequency noise annoyance and sensitivity have no significant differences between different studied ages and sexes. The result also revealed that, a significant correlations exists between sensitivity to low frequency noise and deep mental process [r=0.33, p=0.01]. It was recognized that low frequency nose at 65 dBA can decrease accuracy [p=0.005] and performance [p=0.001] in comparison with reference noise at the same level. Low frequency noise, have impact on mental performance during performing math calculations

[ influences of low frequency noise on mental performance]

Although the evolution of industrial systems toward digital technologies decreased the exposure to high levels of noise, it has created some problems encountered with low level and provoking noise [low frequency noise]. In the present work, the mental performance of students exposed to low frequency and reference noises at low and high levels [45 and 65 dB] were studied. Additionally, other factors such as annoyance, sensitivity to low frequency noise and hearing status of participants were considered. After generating low frequency and reference noises required for the study, a pilot study was conducted. Then, 54 students participated in the main study after preliminary tests. Their mental performances were evaluated with standard psychological tests while they were exposed to low frequency and reference noises at 45 and 65 dBA. The results showed that noise annoyance and low frequency noise sensitivity do not have a significant correlation with age and sex. The results also revealed that, low frequency noise at 65 dB can decrease concentration [P=0.003] and increase response time [P=0.039] of performance in comparison with low frequency noise at 45 dB. On the other hand, reference noise at 65 dB can increase speed [P<0.001] of performance in comparison with reference noise at 45 dB. Low frequency noise can reduce the mental performance and increase its response time