Accession Number : ADA319519

Title :   Prototype Acoustic Monitoring Pad.

Descriptive Note : Final rept. 15 Nov 95-26 Oct 96,

Corporate Author : ARMY RESEARCH LAB ADELPHI MD

Personal Author(s) : Scanlon, Michael V.

PDF Url : ADA319519

Report Date : OCT 1996

Pagination or Media Count : 20

Abstract : The Army Research Laboratory has developed an acoustic sensor that couples extremely well with the human body to detect and monitor heartbeat and lung sounds. A hand-held version of the sensing pad was configured that can be attached to a field medic's hand or glove for combat casualty care. The configuration allows auscultation through headphones by placement of the medic's hand on the torso or limb. Data collected with a palm-sized sensor demonstrate excellent sensitivity, and Fourier analysis clearly demonstrates heartbeat and breath signatures. The sensing pad consists of a fluid-filled bladder that acts as a fluid extension of the body, forming an acoustical conduit to a sensitive hydrophone within the bladder that detects body sounds. The excellent acoustic coupling between a human body, which is mostly water, and a fluid filled sensor pad enables the collection of high-SNR physiological signatures. The choice of a polychloroprene rubber bladder material with an aquacious gel filler optimizes the acoustic impedance matching, because of the similar sound speeds and densities of the pad and skin materials. Airborne acoustic signals, such as ambient noise, do not couple well to the pad because of significant impedance mismatches and noise-canceling materials.

Descriptors :   *COUPLING(INTERACTION), *ACOUSTIC SIGNALS, *MEDICAL SERVICES, *ACOUSTIC VELOCITY, *ACOUSTIC DETECTORS, *BLADDERS, WARFARE, ARMY RESEARCH, MONITORING, WATER, MATERIALS, AIRBORNE, RUBBER, SENSITIVITY, SOUND, CASUALTIES, LUNG, ACOUSTICS, FLUIDS, HUMAN BODY, HYDROPHONES, AMBIENT NOISE, GELS, SKIN(STRUCTURAL), HEART, FOURIER ANALYSIS, FILLING, CONTRACTION, ACOUSTIC IMPEDANCE, IMPEDANCE MATCHING, FILLERS, EARPHONES, CONDUITS, CHLOROPRENES.

Subject Categories : Medicine and Medical Research
      Acoustic Detection and Detectors
      Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE