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. 2016 Dec;13(12):960-968.
doi: 10.1080/15459624.2016.1200723.

Speech intelligibility assessment of protective facemasks and air-purifying respirators

Andrew J Palmiero  1 , Daniel Symons  2 , Judge W Morgan 3rd  2 , Ronald E Shaffer  1
Affiliations

Speech intelligibility assessment of protective facemasks and air-purifying respirators

Andrew J Palmiero et al. J Occup Environ Hyg. 2016 Dec.

Abstract

Speech Intelligibility (SI) is the perceived quality of sound transmission. In healthcare settings, the ability to communicate clearly with coworkers, patients, etc., is crucial to quality patient care and safety. The objectives of this study were to: (1) assess the suitability of the Speech Transmission Index (STI) methods for testing reusable and disposable facial and respiratory personal protective equipment (protective facemasks [PF], N95 filtering facepiece respirators [N95 FFR], and elastomeric half-mask air-purifying respirators [EAPR]) commonly worn by healthcare workers; (2) quantify STI levels of these devices; and (3) contribute to the scientific body of knowledge in the area of SI. SI was assessed using the STI under two experimental conditions: (1) a modified version of the National Fire Protection Association 1981 Supplementary Voice Communications System Performance Test at a Signal to Noise Ratio (SNR) of -15 (66 dBA) and (2) STI measurements utilizing a range of modified pink noise levels (52.5 dBA (-2 SNR) - 72.5 dBA (+7 SNR)) in 5.0 dBA increments. The PF models (Kimberly Clark 49214 and 3 M 1818) had the least effect on SI interference, typically deviating from the STI baseline (no-mask condition) by 3% and 4% STI, respectively. The N95FFR (3 M 1870, 3 M 1860) had more effect on SI interference, typically differing from baseline by 13% and 17%, respectively, for models tested. The EAPR models (Scott Xcel and North 5500) had the most significant impact on SI, differing from baseline by 42% for models tested. This data offers insight into the performance of these apparatus with respect to STI and may serve as a reference point for future respirator design considerations, standards development, testing and certification activities.

Keywords: Communication; facemask; healthcare; respiratory protection; speech intelligibility.

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Figures

FIGURE 1
FIGURE 1. Test System Schematic
*Adapted from NFPA 1981: Standard on Open-Circuit Self-Contained Breathing Apparatus (SCBA) for Emergency Services, 2013 Edition.
FIGURE 2
FIGURE 2
STI Testing Setup inside Hemi-Anechoic Chamber.
FIGURE 3
FIGURE 3
2nd Experimental Condition.
FIGURE 4
FIGURE 4
Boxplot of STI Score by Model at −15 SNR.
FIGURE 5
FIGURE 5
Speech Transmission Index.
FIGURE 6
FIGURE 6
Sound Press per Octave Band
See this image and copyright information in PMC

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