OVERALL DEVELOPMENT OF LUNG SOUND ANALYZING SYSTEM

我们以往的肺音记录分析系统存在以下局限性：1)该系统的机械或操作复杂；2)由于存储体积小，用于a - d转换的波长固定且有限（采样频率为20 KHz时为25.6 ms）； 3)从追踪的肺音中任意提取每个裂纹不容易；4)每个裂纹的频谱分析需要较长的时间。为了解决这些问题，我们利用数字模拟磁带录音机和个人计算机构建了一个新的分析系统。在这个系统中，我们使用了一个商业软件，Wave Master。该系统具有以下优点：1)实时A-D转换或记录是可能的，2)A-D转换的持续时间足够长，可以在一个呼吸相位采样裂纹（采样频率为20khz时为6.553秒），3)我们很容易在显示器上识别一个呼吸相位的每个裂纹，4)可以随意提取任何裂纹或进行FFT分析，5)也可以同时显示时间扩展波形和FFT。为了验证该系统的优越性，我们从16例无痰的IIP患者中采集了80条裂纹，从9例痰量显著（50-300 ml/天）的慢性支气管炎患者中采集了43条裂纹。通过对cracKles的分析，我们可以很容易地确定各组肺音的6个参数（Tb、Tf、IDW、2CD、PF、MF）。结果表明，这种新设备似乎是分析肺部声音的有力工具。

Our previous recording and analyzing system of lung sounds had some limitations as follows: 1) the machinery or the operation of this system was complicated, 2) the length of the waves for A-D conversion was fixed and limited (25.6 ms. at sampling frequency of 20 KHz) due to a small size memory, 3) optional extractions of each crackle from traced lung sounds was not easy, 4) spectral analysis of each crackles required long time. To solve these problems, we constructed a new analyzing system using a digital-analogue tape recorder and a personal computer. In this system, we applied a commercial software, Wave Master.This new system has following merits: 1) real-time A-D conversion or recording is possible, 2) the duration of A-D conversion is long enough to sample crackles in one respiratory phase(6.553 sec. at sampling frequency of 20 KHz), 3) we easily identify every crackles in one respiratory phase on the display, 4) picking up any crackles or doing FFT analysis at will is possible, 5) it is also possible to display time expanded wave forms and FFT simultaneously.To test the superiority of this system, we picked up 80 crackles from 16 IIP patients without sputum production and 43 crackles from 9 patients with chronic bronchitis who had significant amount of sputum (range 50-300 ml/day). By analyses of cracKles, we could easily determine 6 parameters of lung sounds (Tb, Tf, IDW, 2CD, PF, MF) in each group. As the results, this new device was seemed to powerful, tool for the analysis of lung sounds.