Attenuation of ultrasonic noise in the 10-16 kHz frequency range by earplugs

Abstract

The aim of the study was to determine attenuation of earplugs for ultrasonic noise in the frequency range of 10-16 kHz. The attenuation of earplugs in 1/3-octave-bands with the centre frequencies of 10 kHz, 12.5 kHz, and 16 kHz using the REAT (real-ear attenuation at threshold) method based on the measurements of hearing threshold of subjects. The study was carried out for 29 models of earplugs commonly used in the industry designed by various manufacturers, including 13 models of foam earplugs, 10 models of flanged earplugs, 5 models of headband earplugs and one model of no-roll earplugs. The values of the measured attenuation of earplugs are in the range 12.9-33.2 dB for the 10 kHz frequency band, 22.8-35.2 dB for the 12.5 kHz frequency band and 29.5-37.2 dB for the 16 kHz frequency band. The attenuation of earplugs in the frequency range 10-16 kHz has higher values (statistically significant changes) for foam earplugs than flanged earplugs (p = 0.0003 vs. p = 0.0006) or headband earplugs (p = 0.0002 vs. p = 0.04). The tests indicated that there is no uniform relation between the sound attenuation in the frequencies range of 10-16 kH and the catalogue H parameter (high-frequency attenuation value) of earplugs. Therefore, it is not possible to easily predict the attenuation of ultrasonic noise in the frequency range of 10-16 kHz using the sound attenuation data for the normally considered frequency range (up to 8 kHz). Med Pr 2018;69(4):395-402.