Sound Science: World-Class Army Facility Amplifies Auditory Research

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A twig cracking, whispers, a car backfiring, shots in the distance: the importance of a Soldier's ability to hear a wide range of sounds is critical to survival and mission success on the battleField.

In today's military environment, the harshness of various sounds produced by both military and nonmilitary activities can make it difficult for Soldiers to separate useful signals from background noise. A Soldier's ability to hear can be corrupted by physical barriers such as ballistics helmets, mission-oriented protective headgear, communications headsets and hearing protection devices.

Mission accomplishment is paramount, so to determine both the limits of human hearing and the effects of Soldier equipment on battlefield sound perception, the U.S. Army Research Laboratory created the Environment for Auditory Research at Aberdeen Proving Ground, Md. ARL fellow Tom Letowski, and Bruce Amrein, chief of the Visual and Auditory Processes Branch, developed the concept and blueprint of the EAR.

At the facility, ARL researchers conduct basic and applied auditory and speech perception research to help Soldiers improve situational awareness and increase survivability. Research areas include: the perception of acoustic signatures produced by military-relevant sound sources, speech communication in adverse environments, effects of mental and physical workload on hearing, effects of various types of headgear on detection, and identification and localization of specific acoustic signatures.

To support this research, the EAR facility is capable of replicating sounds from a wide range of indoor and outdoor, urban and rural environments.

"The use of controlled space is imperative in order to integrate certain conditions," explained Amrein. "For example, sound sources, reflective surfaces and head-mounted equipment must all be emulated in the controlled setting. The capability to mix in relevant military sounds and have an actual body present to give feedback quantifies the effects and impacts of auditory research."

According to the experts at the facility, the combination of the research spaces and capabilities is unmatched at any military, academic or industrial facility worldwide. The facility currently comprises four indoor areas: the Sphere Room, Distance Hall, Dome Room and Listening Laboratory, as well as one outdoor space, OpenEAR. All spaces are controllable from one room, and the facility can accommodate up to three independent experiments simultaneously.

The Sphere Room was created as an auditory virtual reality space for research in spatial perception, and to evaluate various 3-D system implementations. The room contains 57 loudspeakers in a spherical arrangement and an instrumented listener's station to collect a variety of responses.

"The current version of the listener's station allows us to collect a wide range of overt human responses including speech, direction pointing and screen touching, while future plans include collection of physiological responses," Amrein noted. …