The system involves putting a dual-microphone probe into Sonomax’s uniquely designed SonoFit™ Hearing Protector Plug. When the plug is exposed to a generated sound source, the SonoPass™ system measures the noise reduction (simultaneous sound pressure levels inside and outside the hearing protection device) and applies compensation factors derived from rigorous laboratory testing. The result is a personal attenuation equivalent, yielding an effective personal attenuation rating, or PAR, for each ear of the user.  At the same time, the detailed output is recorded and kept as part of the employees health records.  This not only helps protect the individual, it helps the organization with its regulatory compliance obligations.  

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Sonomax developed and introduced the world to SonoPass™ Proof of Performance Software. It is comprised of our uniquely designed dual microphone insert and our Windows-based
F-MIRE SonoPass™ software.

• Certified individual (F-MIRE) field attenuation measurement in minutes.

• Reliable PAR (Personal Attenuation Rating) for each individuals’ hearing protector

• Dual element microphone measures sound inside and outside the ear.

• Customized protection to optimized noise levels.

• International standards with multi-lingual compatibility.

Methodology – Field Microphone in Real Ear (F-MIRE):

The proposed F-MIRE is a valid alternative to statistical manipulation of population-based hearing protector performance estimates and yield values comparable to “gold standard” REAT testing. The P-PAR is computationally similar to the Noise Reduction Rating (NRR), but it is:

• Obtained via objective measurement rather than relying on user response to stimulus;

• Measured on the subject-fit HPD rather than applying data from sample populations;

• Assessed under realistic use conditions rather than idealized laboratory settings.

A moderate (approximately 85 dB) pink noise source is used as stimulus. A dual-element microphone simultaneously measures sound pressure at the outside surface of the HPD (B’) and beneath the HPD (A’) in illustration to the  right.  A’ is measured using a probe attached to the microphone which is inserted to a sound bore that traverses the length of the HPD.  Sound Pressure Level (SPL) inside and outside the HPD are compared; the difference in dB measures the noise reduction provided by the HPD.

SonoPass™ Field-MIRE measurement system