DESIGN AND CONSTRUCTION OF A CONVERTIBLE HEMI/ANECHOIC ACOUSTICAL LABORATORY FOR TESTING SPACE FLIGHT HARDWARE AT THE NASA GLENN RESEARCH CENTER

摘要

At the NASA Glenn Research Center, science experiment payloads developed for the International Space Station are designed to meet noise emission criteria that promote hearing conservation and speech intelligibility goals. A key component in the successful design of lownoise hardware is the frequent use of acoustical testing as a diagnostic and design verification tool. NASA has designed and constructed a convertible hemi/anechoic Acoustical Testing Laboratory that provides convenient access to accurate and repeatable sound pressure level measurements as well as state-of-the art capabilities for sound power level testing per ANSI S12.34 and ANSI S12.35 using a multichannel PC-based data acquisition system. The ATL consists of a 100 Hz. hemi-anechoic chamber, vibration-isolated to 3 Hz., with 21- ft. by 17-ft. by 17-ft. (h) interior working dimensions and removable floor wedges that allow the facility to be configured as either a hemianechoic or fully anechoic chamber. These characteristics, along with very low design background levels, enable the acquisition of accurate and repeatable acoustical measurements on test articles, up to a full ISS rack in size, that produce very little noise. A separate, sound-isolated control room doubles as a test support equipment enclosure when testing articles that require remote connections to high-noise support equipment and services. Movable modular furnishings facilitate reconfiguration of the enclosure so that data acquisition and test control functions may be easily relocated to an adjacent quiet area. The Glenn Research Center Acoustical Testing Laboratory provides testing services for microgravity space flight hardware developed by NASA and external contractors as well as for commercial products and other non-NASA hardware. The ATL also offers a full range of noise control services to assist payload developers with meeting the ISS noise emission criteria.