Longhini C, Arslan E, Ravenna F, Toselli T, Pedrielli F, Pansini R, Portaluppi F
G Ital Cardiol. 1981;11(1):79-83.
The use of phonocardiography is limited by the lack of standardization of acoustical signal pick-up and of the filters. Moreover, quantitative evaluations are not possible. This limits the analysis of acoustic phenomena and makes confrontation between different laboratories impossible. To avoid these drawbacks we have developed a method based on phonometric principles. Heart sounds of twenty for normal subjects were recorded by an air-coupled microphone with the standard 6 ml cavity. The response curve of the microphone is flat from .2 to 8000 Hz. The signal was measured and stored on an analogic tape recorder together with the ECG. For each subject the 3 weighting networks (A, B and C, according to the American National Standard Institute) and the linear recording (SPL) were used and the peak value of every record was written down in dB-peak. The amplitude spectra were obtained through the FFT algorithm. Normal heart sounds reached a high frequency limit of 170 Hz. with a maximum amplitude of 67 dB SPL, 24 dB A, 42 dB B and 59 dB C. Each spectral pattern can provide a useful reference to compare with pathological acoustical findings.
心音图的应用受到声学信号采集和滤波器缺乏标准化的限制。此外，无法进行定量评估。这限制了对声学现象的分析，也使得不同实验室之间无法进行对比。为避免这些缺点，我们开发了一种基于心音测量原理的方法。用标准的6毫升腔的空气耦合麦克风记录了20名正常受试者的心音。麦克风的响应曲线在0.2至8000赫兹范围内是平坦的。信号与心电图一起被测量并存储在模拟磁带录音机上。对于每个受试者，使用了3种加权网络（根据美国国家标准学会的A、B和C）以及线性记录（声压级），并将每个记录的峰值以分贝峰值记录下来。通过快速傅里叶变换算法获得幅度谱。正常心音的高频极限为170赫兹，最大幅度为67分贝声压级、24分贝A、42分贝B和59分贝C。每个频谱模式都可以为与病理性声学发现进行比较提供有用的参考。
