Journal of North Khorasan

Abstract Background & Objective: Accompanying with industrialization, noise pollution is coming to be a serious problem in the workplace. Since some of peripheral infections have been caused by Escherichia coli bacteria, the purpose of this study was to evaluate the effect of single-frequency noise pollution on the growth of Escherichia coli. Material & methods: An audio amplifier was designed and constructed in order to produce sound waves of multiple 8 different frequencies. Centers of frequency were included 63.5, 125, 250, 500, 1000, 2000, 4000 and 8000 Hz. The sound intensity was considered as well of 30 dB. In each frequency, ten medium of E-Coli were studied. Mediums were divided into two groups and were incubated in the same conditions one group in the exposure of sound waves (experimental group) and the other without a sound wave (controls). The bacteria were incubated at 37°C for 24h. Then bacterial colonies were counted. The results of the experimental and control groups were analyzed by with MATLAB2011 and presented with t-test. Alpha level of 0.05 was considered significance. Results: The results showed that the bacterial growth rate significantly increases in frequency of 63.5, 1000, 2000 and 4000 Hz (p<0.05), such that bacterial growth rates also increase through the frequency increasing. Bacterial growth rate was significantly reduced in 8000 Hz (p<0.05). In other frequencies, the bacteria growth rate did not follow a specific pattern and their changes were not significant. Conclusions: This study showed that single frequency noise pollution has effect on bacteria growth and its effects are increased on within the ear sensitivity. Therefore this area could provide fertile ground for the growth of bacteria, thus controlling the audio frequency is proposed in industrial environments.