A Comparison Study of Foam versus Custom Silicone Earplugs Used as Part of an Intelligent Electronic Hearing Protector System

Abstract

During the development of an intelligent hearing protection and communication system the attenuation of two different earplugs were measured. Both earplugs were measured separately and in combination with earmuffs. Foam earplugs and custom-moulded silicone earplugs were both used. The hearing protection system in question is able to measure the ear canal with respect to leaks. If a leak is detected, the system will warn the user. The measurements show that the foam plug gives higher attenuation than the silicone plug at all frequencies, but particularly at frequencies below 2 kHz. It has a steadily increasing attenuation from 30 dB – 43 dB over the frequency range 125 Hz – 8 kHz. The silicone plug attenuates around 26 dB, from 125 Hz – 1 kHz. Above this range, the attenuation increases to approximately 40 dB. With extra earmuffs added, the attenuation is 40 dB or better at all frequencies except 125 Hz, and the two plugs offer nearly identical protection. The results show that the mean and standard deviation of the attenuation for the foam earplug is as good as for an optimally fitted earplug. In the case of the silicone earplug, the mean attenuation is comparable to a typical custom earplug, but the standard deviation is better than comparable earplug. This finding is a result of the leakage control acting as a ’supervisor’ in the fitting of the earplugs.