Acoustic impedance of the maternal abdomen.
Acoustic impedance of the maternal abdomen.
复制标题
产妇腹部的声阻抗。
DOI：
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发表时间：
1993
影响因子：
2.4
通讯作者：
D. Sunkel
中科院分区：
文献类型：
--
作者：
G. R. Wodicka;A. Lam;V. Bhargava;D. Sunkel
用于监测胎儿心脏、呼吸和运动声音的接触式传感器正在开发中，其灵敏度和带宽都在增加。为了了解母亲腹部的固有声学特性及其与这些传感器的相互作用，在怀孕的最后三个月期间测量了9名妇女的驱动点阻抗Z（j Ω）。接触面积为2.85平方厘米的机电振动器产生10和500赫兹之间的腹部振动，并测量所产生的力和加速度。在对加速度信号进行数字积分以获得速度并去除振动器和腹部之间的耦合的巨大影响之后，使用谱技术估计Z（j ω）。Z（j ω）的虚部描绘了在低频下的主导顺应性效应，在28 +/-16 Hz（平均值+/- s.d.）的频率下的共振，以及在较高频率下的主导质量效应。Z（j ω）的真实的部分随频率稳定地增加。当允许R精确地模拟Z（j Ω）的真实的部分的频率依赖性时，串联电阻-质量-柔度（R-M-C）电路很好地模拟了Z（j Ω）的这些特性。M的估计元素值为6.6 +/- 2.2 x 10（-3）kg，C为2.1 +/- 1.4 x 10（-3）m/N，R约为10 Ns/m（共振时），与其他身体组织（如大腿）的估计值相似，但与经常研究的胸壁的估计值有很大差异。
Contact sensors to monitor fetal heart, breathing, and movement sounds with increased sensitivity and bandwidth are under development. To understand the inherent acoustical properties of the maternal abdomen and its interaction with these sensors, the driving-point impedance Z(j omega) was measured in nine women during their last trimester of pregnancy. An electromechanical shaker with a contact area of 2.85 cm2 produced abdominal vibrations between 10 and 500 Hz, and the resulting force and acceleration were measured. After digitally integrating the acceleration signal to obtain the velocity and removing the massive effects of the coupling between the shaker and the abdomen, Z(j omega) was estimated using spectral techniques. The imaginary part of Z(j omega) depicted a dominant compliance effect at low frequencies, a resonance at a frequency of 28 +/- 16 Hz (mean +/- s.d.), and a dominant mass effect at higher frequencies. The real part of Z(j omega) increased steadily with frequency. A series resistance-mass-compliance (R-M-C) circuit modeled these characteristics of Z(j omega) well when R was allowed to exactly mimic the frequency dependence of the real part of Z(j omega). Estimated element values of 6.6 +/- 2.2 x 10(-3) kg for M, 2.1 +/- 1.4 x 10(-3) m/N for C, and roughly 10 Ns/m for R (at resonance) were similar to those estimated for other body tissues such as the thigh but quite different from that of the often-studied chest wall.