Expandable Earplug With Smart Custom Fitting Capabilities

摘要

For hearing protection to be made effective, the research needs established by NIOSH (National Institute for Occupational Safety and Health) are to find a way for workers to be individually fitted and to offer them increased comfort and the ability to hear speech and warning signals.To address these issues, a new concept has been developed; a re-usable earplug that is custom-fitted thanks to silicon injection between a hard core and a soft expendable envelope. A miniature bore in the hard core is used to determine the sound pressure level difference across the earplug and for real time monitoring of the acoustic seal during the injection process until an adequate fit has been reached.Another benefit of this measuring capability is the development of a field method to estimate the noise attenuation obtained by such expandable earplugs as worn in the workplace. This estimation uses a statistical approach to link subjective attenuation with objective measurement of the Noise Reduction.Further developments include inserting filtering elements in the earplug; passive filters for selective sound attenuation and active filters to let the worker hear speech and warning signals.