At any time, there is a rich spectrum of acoustic energy in the atmosphere at frequencies below our hearing range. These low-frequency sounds, known as infrasound, can propagate for distances of thousands of kilometers without substantial loss of energy. Their measurement can provide new insight in understanding atmospheric events like convective storms, shear-induced turbulence, acoustic gravity waves, microbursts, hurricanes, and clear air turbulence (CAT). The team at NASA Langley has developed a small and extremely sensitive infrasound detection system that has been tested in the field, successfully transferred to Department of Defense (DOD) and Department of Energy (DOE) agencies, and licensed to a manufacturer (PCB Piezotronics, Inc. of Depew, New York). This system has the advantage of portability, allowing for rapid deployment to warn against and track impending disasters like tornados.

Over the past four years, the Langley team not only successfully designed and developed the system “Extreme Low Frequency Acoustic Measurement System for Subterranean, Seismic, and Environmental Detection,” but successfully engaged university experts, other federal agencies and industry through a concerted outreach program. During the design and development effort in 2007, representatives from Extreme Endeavors, Inc.; PCB Piezotronics; and Georgia Tech University were invited to visit Langley facilities to observe the performance of subcomponents. At that time, ideals were shared that led to the development of optimized portable system design in 2008.

Performance of the portable system in lab tests and field tests (performed by Extreme Endeavor’s engineers in West Virginia) was presented at the 2008 Military Sensing Symposium, Laurel, Maryland. As a result, DOD personnel visited the infrasonic system development laboratory several times during 2009 to discuss their interests and to observe lab and field tests. This led to the signing of an interagency agreement in 2009, through which NASA delivered 16 systems to the DOD for its use. Four systems were delivered to Sandia National Laboratories for long-term testing there. In March 2010, another agreement between the DOD and NASA Langley allowed the installation of an infrasonic field array and the performance of numerous experiments at Langley, which continue to be in use now.