Evaluation of the Changes in Sound Absorption Coefficient of Some Commonly Used Earmuffs in Laboratory Conditions

Using a hearing protection device is one of the ways to control noise pollution in the industry. The purpose of the present study is to evaluate the changes in the sound absorption coefficient of some commonly used earmuffs in laboratory conditions at various sound levels and frequencies.

In this study, four earmuff models, including TASCO2550, AKHAVAN (VENUS-740), 3M optime98, and Parkson ABZ, were prepared. The absorber of the earmuffs was then cut to a diameter of 3 cm and a thickness of 1.2 cm. The absorption coefficient of each sample was measured using an impedance tube and VA-Lab4 software at three sound levels of 75, 85, and 95 dB. Finally, the data were analyzed using SPSS software.

There was no significant difference in the average absorption coefficient between sound levels of 75, 85, and 95 dB. However, in middle and high frequencies, the average absorption coefficient increased. TASCO2550 earmuff absorbent samples showed the highest absorption coefficient at frequencies of 2000-2500 Hz. While AKHVAN (VENUS-740) and 3M optime98 absorbent samples showed the highest average absorption coefficient at the frequency of 4000 Hz. Also, The Parkson ABZ absorbent sample had the highest average absorption coefficient at a frequency of 5000 Hz. In general, The TASCO2550 earmuff absorbent sample showed the highest absorption coefficient, while the 3M optime98 absorbent sample showed the lowest absorption coefficient.

By selecting an earmuff with efficient absorber, we can increase sound absorption rate to achieve the desired results of reducing noise pollution.