24 / 3174/, 2004.Ĭhanging compression ratio with compressor corrected speed change, causes changes in relative air densities and flow velocities in the stages. Data comparison for all three earplugs has not revealed any significant differences in soldier performance although the yellow (level dependent) earplug resulted in slightly better performance than two others. Participants were asked to detect, recognize and localize various speech and environmental stimuli. Within each group there were four listening condition: open ears in quiet and noise and protected ears in quiet and noise.
Group one used the yellow side of the combat arms earplug, group two used the green side of the earplug and group three used the EAR foam plug. There were three groups of participants of 12 listeners each. The rings vary in diameters to provide the same distance of two meters between each loudspeaker and the listener’s head. The rings are separated vertically and located at 0º, 30º, and 60º elevation angles with respect to the position of the listener’s head. Each ring consists of 12 loudspeakers separated by 30º angles.
The participants were seated in the center of an array of 36 loudspeakers distributed over three circular rings plus one loudspeaker located at the top of the array (37 loudspeakers total). The CAE is new to the Army’s inventory and its impact on soldier performance has not been yet well determined, The purpose of this project was to determine the effects of CAE on the soldier’s ability do detect, recognize, and localize sound sources in various listening conditions. The combat arms earplug has two sides, one side (yellow) is the level dependent earplug and the other side (green) is the traditional triple-flange earplug. Army recently approved the use of the combat arms earplug (CAE) that is an expanded American version of the level dependent earplug developed at the French-German Institute. When the attenuation characteristics are not engaged, the earplug allows relatively unimpeded verbal communication. When engaged the level dependent hearing protection attenuates the dangerous high level and high frequency component of the impulse noise. It allows verbal communication in relatively normal ambient noise levels, provides protection specifically against impulse noise and can be packaged at a price for mass distribution. A possible solution to the problem is the use of level dependent hearing protection. Although the current hearing protective devices are effective they are not conducive to verbal communication. The noise hazards on the battlefield are capable of creating temporary or permanent hearing loss. Soldiers in today’s combat environment need hearing protection that is responsive to their communication needs.