The viability of hearing protection device fit-testing at navy and marine corps accession points

Abstract

Introduction:The viability of hearing protection device (HPD) verification (i.e., fit-testing) on a large scale was investigated to address this gap in a military accession environment.Materials and Methods:Personal Attenuation Ratings (PARs) following self-fitted (SELF-Fit) HPDs were acquired from 320 US Marine Corps training recruits (87.5% male, 12.5% female) across four test protocols (1-, 3-, 5-, and 7- frequency). SELF-Fit failures received follow-up to assess potential causes. Follow-up PARs were acquired (Experimenter fit [EXP-Fit], followed by Subject re-fit [SUB Re-Fit]). EXP-Fit was intended to provide a perception (dubbed “ear canal muscle memory”) of what a correctly fitted HPD should feel like. SUB Re-Fit was completed following EXP-Fit to determine whether a training recruit could duplicate EXP-Fit on her/his own without assistance.Results:A one-way analysis of variance (ANOVA) (N=320) showed that SELF-Fit means differed significantly between protocols (P < 0.001). Post-hoc analyses showed that the 1-freq SELF-Fit mean was significantly lower than all other protocols (P < 0.03) by 5.6 dB or more. No difference was found between the multi-frequency protocols. For recruits who were followed up with EXP-Fit (n=79), across all protocols, a significant (P < 0.001) mean improvement of 25.68 dB (10.99) was found, but PARs did not differ (P = 0.99) between EXP-Fit protocols. For recruits in the 3-freq and 5-freq protocol groups who experienced all three PAR test methods (n=33), PAR methods differed (P < 0.001) but no method by protocol interaction was found (P = 0.46). Post hoc tests showed that both EXP-Fit and SUB Re-Fit had significantly better attenuation than SELF-Fit (P < 0.001), but no difference was found between EXPFit and SUB Re-Fit (P = 0.59). For SELF-Fit, the 1-freq protocol resulted in a 35% pass rate, whereas the 3-, 5-, and 7-freq protocols resulted in >60% pass rates. Results showed that once recruits experienced how HPDs should feel when inserted correctly, they were able to properly replicate the procedure with similar results to the expert fit suggesting “ear canal muscle memory” may be a viable training strategy concomitant with HPD verification. Fit-test duration was also measured to examine the tradeoff between results accuracy and time required to complete each protocol.Discussion:Results from this study showed the critical importance of initial selection and fitting of HPDs followed by verification (i.e., fit-testing) at Navy and Marine Corps accession points. Achieving adequate protection from an HPD is fundamentally dependent on obtaining proper fit of the issued HPD as well as the quality of training recruits receive regarding HPD use.

Verifying earplug attenuation and evaluating the effectiveness of one‐on‐one training along with earplug fit testing at nine facilities in China

“…This training strategy has been adopted in numerous studies 10,21,23,24 and PARs improved significantly across these studies. Federman and Duhon 32 evaluated three different training paradigms with 79 US Marine Corps training recruits. In one paradigm, individualized training included an experimenter fit which dramatically improved the mean PARs by 26 dB compared with the initial self‐fit.…”

Improving Hearing Protection Device Noise Attenuation Through Fit-Testing in an Occupational Health Clinic

“…Similar to other findings, the results in this QI project demonstrated that HPD fit testing was an effective method for training employees to properly insert HPDs (Federman & Duhon, 2016; Federman et al, 2021; Gong et al, 2019, 2021; Murphy et al, 2016; Sayler et al, 2018; Smith et al, 2014). In addition, this project showed that an evidence-based practice (i.e., using HPD fit testing to validate expert-fitted HPDs followed by participant return demonstration of self-fit using muscle memory to replicate proper fit) outlined by Federman and Duhon (2016) could be successfully implemented by staff in an occupational health clinic. Using PDSA cycles to evaluate and adapt as the project progressed was an effective framework to improve processes.…”

“…To reduce the time for testing, three frequencies (500 Hz, 1,000 Hz, and 2,000 Hz) were utilized for assessment. Several researchers demonstrated that testing more than these frequencies failed to significantly affect PARs (Federman & Duhon, 2016; Murphy et al, 2016). The system was calibrated daily according to manufacturer instructions before testing was conducted.…”

“…An estimate of the field value of attenuation based on NRRs established in laboratory settings is a poor indicator of personal attenuation due to variability in the size and shape of individual ear canals (CDC, 2015). Furthermore, HPDs that fit poorly or are improperly worn decrease the likelihood of achieving adequate noise protection (Berger, 2003; Federman & Duhon, 2016).…”

“…PAR was reassessed to demonstrate the participant had achieved proper HPD fit. The authors’ findings indicated that expert HPD fitting and participant return demonstration with fit-test validation was an effective training method that significantly improved PARs (Federman & Duhon, 2016). Studies by Gong et al (2019), Gong et al (2021), Sayler et al (2018) and Ullman et al (2021) have confirmed that HPD fit testing is an appropriate training method to ensure proper HPD fit and prevent occupational NIHL.…”