Investigating the Absorbent Transmission Loss of Some Common Earmuffs in One-Third Octave Band Frequency Based on the Impedance Tube Method

Choosing the suitable hearing protection for workers as part of the Hearing Conservation Program was introduced as a final measure. This study aimed to investigate the absorption and transmission loss of common earmuffs at one third octave band frequencies using the impedance tube method.

An analytical-experimental study was carried out on absorbers of four earmuff models. The transmission loss of the absorbers was measured using the impedance tube by the transfer function method, in accordance with the ISO 10534-2 standard. Data analysis was conducted using the paired-samples t-test and analysis of variance (ANOVA) with SPSS software.

The highest and lowest mean transmission losses measured in absorbers were 27.5 dB and 0.3 dB, respectively. The results showed a significant difference in the mean transmission loss between absorber A and absorbers B, C, and D, as well as between absorber B with absorbers A and D, across all measured frequencies (P < 0.05). Moreover, the results showed a significant difference in all frequencies before and after in absorbers A, B, and C (P < 0.05).

When comparing earmuff absorbers, it is evident that their performance in transmission loss and efficiency varies across different frequencies. In addition, most of the earmuffs examined in the study showed a decrease in transmission loss at low frequencies as the frequency increased. However, above2 kHz, an increasing trend in transmission loss was observed. These results need to be noted when choosing suitable hearing protection for workers in industries.