Page 10 - Jul2009

THE ENVIRONMENT FOR AUDITORY RESEARCH
Paula P. Henry, Bruce E. Amrein, and Mark A. Ericson
U.S. Army Research Laboratory Aberdeen Proving Ground, Maryland 21005-5425
“The combination of research spaces and capabilities is unmatched at any military, academic, or industrial facility world-wide.”
Background
Army personnel are required to
perform missions while
immersed in a wide range of
ambient sounds. The desired acoustic
signals reaching a soldier’s ears are
often physically corrupted by head-
worn equipment and unwanted
mechanical and natural sounds. To
study hearing abilities in situ, the
reflective surfaces, sound sources, and head-mounted equipment must be emulated in a controlled setting. Acoustic recreations of rural and urban soundscapes mixed with relevant military sounds need to be presented to lis- teners in controlled laboratory spaces to quantify the effects of auditory environments on listening tasks. For this reason, the Environment for Auditory Research (EAR) facility was conceived and constructed at the U.S. Army Research Laboratory (ARL) at Aberdeen Proving Ground, Maryland. This new facility will be used to study the ability of soldiers to detect, identify, and localize sounds in realistic opera- tional sound fields and to develop equipment to maximize human communication performance.
The Environment for Auditory Research facility is operat- ed by the Auditory Research Team (ART) of the Visual and Auditory Processes Branch (VAPB)—part of the Human Research and Engineering Directorate (HRED) of the ARL. The ART’s mission is to conduct basic auditory and speech per- ception research applicable to ground troops, i.e., dismounted soldiers. Areas of research include the perception of simple and complex sounds, and the effects of hearing protection, head gear, and workload on performance of the human auditory sys- tem. Specific types of experiments to be conducted in the EAR facility include auditory localization and situational awareness, as well as speech, distance, and motion
perception. The EAR facility is
designed to be reconfigurable to simu-
late a wide range of indoor and out-
door acoustic environments.
research efforts such as a cooperative research and development agreement (CRDA). ARL welcomes inquiries about the potential for future collaborations or use of the research facility.
The EAR facility spaces are flexible to accommodate different types of experi- ments. The acoustic absorption charac- teristics can be modified from nearly ane- choic to moderately reverberant. The
sound sources, e.g., loudspeakers, can be repositioned around the listener and hidden from the listener’s field of view to min- imize visual cues for auditory source location. The ambient noise floor for all research spaces meets noise criterion fifteen (NC-15) specifications when the heating, ventilation and air conditioning (HVAC) system are operating. With the HVAC system off, the spaces are at or below hearing threshold levels. A diagram of the EAR facility is shown in Fig. 1.
The EAR facility encompasses four indoor spaces plus one outdoor space, all coordinated from a single Control Room. First, the Sphere Room was created for research in spatial perception and includes loudspeakers located as if they were connected to a sphere. Second, the Dome Room was created for research in auditory localization with a much denser array of loudspeakers and can be configured to evalu- ate perception of sound in a hemispherical shape. Third, the Distance Hall was created for research in distance estimation and auditory depth perception and is shaped like a rectangu- lar box. Fourth, the Listening Lab was created for research in speech perception and enables evaluation of up to ten listen- ers at one time, as well as testing of various sound reproduc- tion systems. Lastly, the OpenEAR outdoor portion of the facility was designed for auditory research in real-world out- door environments.
ARL is committed to providing access to the space for any researchers who wish to take advan- tage of its unique capabilities. Mechanisms through which this can occur include test services agree- ments (TSAs), where individuals rent the space and/or use personnel from the ART for collection of specific data; visiting scholar programs in which researchers spend a set amount of time working in the facili- ties; and collaborations through joint
Fig. 1. Layout of the four test chambers in the EAR facility.
The Environment for Auditory Research 9