Host: The Japan Society of Mechanical Engineers
Name : Dynamics and Design Conference 2018
Date : August 28, 2018 - August 31, 2018
In recent years, earplugs with analog acoustic band pass filters have been suggested. These earplugs could let workers in noisy factories to protect their ears and, at the same time, to hear the necessary sounds for communicating with colleagues, noticing danger alarm sounds, and detecting equipment failure noise, etc. However, some doubt has been still cast upon sufficient protection of the workers' ears particularly in low frequency range because of the relatively wide passing frequency ranges of sounds. There has been a clear need for the earplugs which could finely control the passing amount and range of sounds appropriately for each working environment. For fine tuning of resonant frequencies, we propose the simple structured earplug implemented with the filter consisting of a micro-orifice, a flexible elastic plate and a small weight. In current study, first of all, the frequency response of the proposed earplug is theoretically modeled by the transfer matrix method with each consisting component. Secondly, the theoretical model is tested experimentally. We obtained the results, which confirm the validity of the theoretical model. It has been also clarified that the proposed earplugs have the capabilities to insulate noise sufficiently in low frequency range and, at the same time, to efficiently pass 1k-2k Hz ranges of the sounds. Further fine tuning could be expected, by changing the detailed properties of the components.
