Improved phonocardiogram system based on acoustic impedance matching.
Improved phonocardiogram system based on acoustic impedance matching.
复制标题
基于声阻抗匹配的改进心音图系统。
DOI：
10.1152/ajpheart.1980.238.4.h604
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发表时间：
1980
期刊：
影响因子：
--
通讯作者：
F. Barnes
中科院分区：
文献类型：
--
作者：
R. Schwartz;J. Reeves;I. Sodal;F. Barnes
We considered that phonocardiographic recording could be improved 1) by minimizing the acoustic impedance mismatch between the precordial tissue and transducer, 2) by optimizing the configuration of the impedance-matching medium and transducer design, and 3) by storing signals in digital form through analog-to-digital conversion of analog recordings made at the bedside. The use of an aqueous coupling medium to improve energy transmission increased signal voltage approximately 100-fold over presently used commercial devices. Further match to the crystal was achieved by a concentrating horn configuration for the aqueous medium. Measured frequency response of the device in the range 1 Hz to 1 kHz was better than two other commercially tested microphones. Inspection of comparative phonocardiograms showed more information from the new device than from the two other commercial devices. Unfiltered digitized signals, using our microphone in normal subjects, demonstrated good beat-to-beat repeatability, but analog filtering to obtain the conventional phonocardiogram showed significant loss of information. The new instrument appears to be superior to those commercial devices tested in recording heart sounds.
