The Influence of Conventional Earmuff Sound Absorbers on Psychoacoustic Factors: A Laboratory Study

Aim: 
Traditional indicators used for evaluating hearing protectors do not capture their impact on psychoacoustic parameters. Therefore, this study aimed to analyze commonly used absorbers in earmuffs and their influence on psychoacoustic indicators, specifically focusing on roughness and fluctuating strength.
Methods: 
This intermittent and descriptive-analytic study involved measuring psychoacoustic indicators at sound pressure levels (SPLs) of 75, 85, and 95 dB using white noise and an impedance tube for single- and double-layered absorbers. SPSS software was used for statistical analyses, including reporting descriptive statistics (mean and standard deviation) for quantitative data. The effects of the absorber on psychoacoustic parameters were examined using the independent statistical test.
Results: 
The study findings revealed that the average values of roughness and fluctuating strength parameters decreased across all four absorbers as sound pressure intensity increased. The statistical test results indicated that there were no significant differences in psychoacoustic parameters among the absorbers at the three pressure levels tested, regardless of the presence or absence of an absorber (all P > 0.05). However, the statistical test showed a significant difference (P = 0.032) for the roughness parameter among the four absorbers at 95 dB level. In addition, for the fluctuating strength parameter, significant differences were observed among the four absorbers at 75 dB level (P = 0.036) and 95 dB level (P = 0.003).
Conclusion: 




Controlling noise to reduce psychoacoustic parameters such as roughness and fluctuating strength at SPL above 85 dB can be achieved effectively using earmuffs equipped with single-layered absorbers compared to those with double-layered absorbers.