Determining the Characteristics of Sound Pressure in Occupational Exposure to Military Vessels: A Descriptive Study

Noise annoyance is considered a significant injury in military personnel and has the ability to affect their combat performance. The purpose of this study is to determine the characteristics of sound in the occupational exposure of employees to military vessels.

This cross-sectional study was conducted on N-class and T-class vessels near Mahshahr city in 2022. Sound measurement and octaband analysis were done using sound meter and acoustic calibrator. In N-class and T-class vessels, the analysis of the sound pressure level was analyzed in the stationary state and in the state while moving with engine speed of 1300 and 1700 rpm. The collected data were analyzed in Minitab 21 software.

The findings showed that the sound pressure level in the switched on state is less than the standard limits at frequencies of 250, 500, 1000, 2000, 4000 and 8000 Hz. But in the on state during movement and with the engine speed of 1700 rpm in both N-class and T-class vessels, engine number 2 has the highest sound pressure level with a difference of 18.8 and 14.9 dB compared to the standard limits. Also, at the frequency of 250 Hz, among the distance measurement of different engines, the biggest difference in sound pressure level (-29.6 dB) with the standard limits is related to the right engine of the N-class vessel.

The findings of the present study demonstrated that the sound pressure level in the switched on state does not cause any damage to the hearing of military personnel, because in all the measured frequencies, the sound pressure level was reported to be lower than the standard limits. It is recommended to use personal protective equipment for employees during military operations or to install a high-performance absorber in the cabin of both vessels during occupational exposures to reduce the harmful effects of noise.