Field assessment of acute auditory responses to environmental exposures in close quarters tactics training

Abstract

Objective

The purpose of this study was to evaluate auditory performance of military instructors as part of a training course involving noise and blast exposure. Boothless audiometry was used to estimate the test-retest reliability of the auditory measures under realistic field conditions and to determine risk of acute auditory injury during standard training practices.

Design and study sample

Thirteen U.S. Marine instructors participated in study activities. An audiologic testing suite embedded in a noise-attenuating headset was used to test various tone detection tasks on subjects after exposure. Acoustic exposures were captured with sound level meters.

Results

Boothless audiometry provide highly repeatable results for various tests of auditory performance in the field environment. In this test population, changes in auditory performance pre- and post-noise exposure were minimal for most measures. The notable exception was binaural (NoSπ) tone detection, which showed significant degradations both as a function of pre- and post-noise exposure on the same day and as a result of cumulative noise exposure over the period of the study.

Conclusions

Study outcomes are consistent with prior laboratory and epidemiological work and suggest a link between the binaural processes required for NoSπ detection and the hearing-related issues reported by blast-exposed service members.

Keywords:

• Boothless audiometry
• hearing conservation/hearing loss prevention
• masking level difference
• noise

Acknowledgements

The authors thank Dr. Kamimori and his colleagues at the Walter Reed Army Institute of Research for their collaborative efforts to support this research. We thank the leadership and other Marines at Marine Corps Base Camp Pendleton for their time, experience, and subject matter expertise in allowing this research to be conducted. We also thank Ms. Rebecca Holtzman, Mr. Antony Bashful, and Ms. Izabelle Sweet for their assistance in the data collection process at Camp Pendleton. And we thank CDR Josh Duckworth and the CONQUER program that he leads for materiel support in the execution of this study. Material has been reviewed by the Walter Reed Army Institute of Research. There is no objection to its publication. The investigators have adhered to the policies for protection of human subjects as prescribed in AR 70–25. The identification of specific products or scientific instrumentation is considered an integral part of scientific endeavor and does not constitute endorsement or implied endorsement on the part of the author, DoD, or any component agency. The views expressed in this manuscript are those of the authors and do not necessarily reflect the official policy of the Department of Defense or the U.S. Government.

Disclosure statement

The authors declare no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Data availability statement

The data that support the findings of this study are available from the corresponding author, DK, upon reasonable request.

Additional information

Funding

This project was supported by the Joint Program Committee-5/Military Operational Medicine Research Program (JPC-5/MOMRP) BAA Award 15-, W81XWH-16-2-0001. Defense Health Program 2018 NDAA Section 734 Working Group Line of Inquiry 1.