In combat casualty and civilian environments, an unmet need exists for a stethoscope that can hear heart and especially breathing sounds while inside helicopters, fixed-wing aircraft, or ambulances where noise levels preclude auscultation with standard stethoscopes. Without this capability, patients can suffer from unidentified collapsed lungs or loss of intubation integrity with the threat of loss of life. A conventional acoustic stethoscope will not function in background noise levels beyond ...