Bone Conduction Systems for Full-Face Respirators: Speech Intelligibility Analysis

Report No. ARL-TR-6883
Authors: Kimberly A. Pollard; Lamar Garrett, Phuong Tran
Date/Pages: April 2014; 38 pages
Abstract: Difficult environments, such as Chemical, Biological, Radiological, Nuclear, and Explosive (CBRNE) environments, pose a unique communication challenge. Effective communication is essential to stay safe in these environments, yet safety gear itself impedes communication. Personal protective equipment (PPE) (e.g., full-face respirators) and noisy decontamination devices (power sprayers, etc.) can impede successful speech transmission. Bone conduction communication systems are a promising solution. These systems are relatively insensitive to background noise and can capture speech directly from a user's skull vibrations, before airborne speech is disrupted by a respirator. To assess the potential of bone conduction systems for use by encapsulated personnel, three communication systems were tested for speech intelligibility using the Modified Rhyme Test (MRT). Sixteen participants wore the M50 Joint Service General Purpose Mask (JSGPM) full-face respirator and communicated via radio using three different communication systems in two levels of background noise. A bone conduction earpiece performed best, followed by a mask-mounted bone conduction system. Both bone conduction systems outperformed the currently-fielded air conduction communication system. The results support the use of bone conduction technology for improved encapsulated communication, which may improve safety and effectiveness for CBRNE personnel. Results are discussed and recommendations are provided.
Distribution: Approved for public release
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Last Update / Reviewed: April 1, 2014