Electronic Stethoscope for Use in Helicopter Noise Environment

In the high noise environment of fixed and rotary wing aircraft used for casualty evacuation, a critical need exists to detect normal vs. pathologic heart and breath sounds and discriminate among their components. Evaluations by the Army staff at theU.S. Army Aeromedical Research Laboratory has demonstrated that no such capability exists whether in standard acoustic stethoscopes or electronic noise-canceling stethoscopes. In Phase I using a novel approach that employed contact sensors directlycoupling the heart and breath sounds to piezoelectric sensors, Active Signal Technologies developed a system that electronically conditioned signals from these sensors so that they could be heard in that 105 dBA environment of a Blackhawk helicopter. Theresulting prototype showed a 10 dB+ improvement over existing stethoscope technology. The Phase II program will build on the enabling technology of Phase I, enhancing the signal to noise properties of the sensors, miniaturizing the electronics, and addingactive noise reduction capability to the system. The final product will be a device that meets both the detection and discrimination requirements of the Army and does so in a form factor that is consistent with a conventional stethoscope.The anticipatedbenefits from this technology will include increased capability of the medics from all the services to better track the progress or deterioriation of patients who are being evacuated in fixed and rotary wing aircraft. In the civilian arena, medevacs arewithout- and in need of this same capability as are ambulances where high background noise and vibration presents the paramedic with challenges to hearing breath and heart sounds of patients on the way to treatment centers. The devices contain mostly cotsparts and could be manufactured at costs that would be affordable to all of the above groups.