Electronic Stethoscope for Use in Helicopter Noise Environment

"Active Signal Technologies proposes to develop an active noise reduction (ANR) stethoscope that will enable detection and discrimination of heart and breathing sounds in the high noise environment of a UH-60 BlackHawk helicopter. We will enhance ourdirect contact sensor technology, which already provides state-of-the-art physiological signal detection and passive noise rejection, to better match the mechanical impedance of soft tissue and electrical impedance of the headphone/earplugs. Our currentsystem has no air cavities or acoustic tubes and discriminates against all airborne noise leakage. Its effectiveness against all disturbances coupled through the body, whether airborne or structure borne, will be enhanced through frequency-domaindigital-filtering ANR algorithms similar to those used in speech recognition. Since Active Signal's passive noise reduction stethoscope already exhibits excellent performance and the ANR approach does not require any additional sensors or actuators, ourprogram starts with established hardware and can move forward aggressively on the ANR implementation. In Phase I we will deliver an enhanced passive noise reduction stethoscope and will demonstrate the ANR on a workstation simulation using prerecordeddata. In the Option we will interface the stethoscope to the workstation and conduct a real-time ANR demonstration in the most challenging noise environment. Noise immune auscultation is a pivotal techno