Inter-laboratory comparison of three earplug fit-test systems.

Area of Science:

• Occupational Safety and Health
• Audiology
• Acoustics

Background:

• Accurate earplug fit-testing is crucial for effective hearing protection.
• Existing fit-test systems require validation against established laboratory methods.
• Variability in fit-test results necessitates understanding contributing factors.

Purpose of the Study:

• To compare the performance of three commercial earplug fit-test systems against laboratory-based real-ear attenuation at threshold (REAT) measurements.
• To evaluate the agreement between headphone-based fit-test systems and soundfield-based REAT measurements.
• To identify potential factors influencing the accuracy and reliability of earplug fit-test systems.

Main Methods:

• Four laboratories, including NIOSH, Honeywell, Michael & Associates, and USAARL, participated in the study.
• The Howard Leight Airsoft earplug was tested on twenty subjects at each laboratory.
• Fit-test systems (NIOSH HPD Well-Fit, Michael & Associates FitCheck, Honeywell VeriPRO) were compared to ANSI/ASA S12.6-2008 REAT measurements.

Main Results:

• Michael & Associates lab reported the highest average attenuations and smallest standard deviations.
• NIOSH lab reported the lowest average attenuations and largest standard deviations.
• FitCheck and HPD Well-Fit showed approximately ±2 dB agreement with ANSI REAT, while VeriPRO underestimated results. Standard deviations for FitCheck and HPD Well-Fit were ±2 dB, compared to ±4 dB for VeriPRO.

Conclusions:

• FitCheck and HPD Well-Fit systems offer reasonable agreement with laboratory REAT measurements for earplug attenuation.
• The VeriPRO system may underestimate hearing protection levels, potentially compromising worker safety.
• Variability in results suggests that administrator experience and task design may influence fit-test outcomes.