Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 W Green Street, Urbana, IL 61801, USA.
Hear Res. 2010 May;263(1-2):216-23. doi: 10.1016/j.heares.2010.02.013. Epub 2010 Mar 1.
When using bone vibrator transducers for clinical measurements, the transfer of energy from the bone driver depends on the impedance match between the driver and the load (human mastoid or otherwise) to which the driver will be applied. Current clinical calibration methods are incapable of quantifying this impedance mismatch, hence they fail to account for inter-subject variations of the energy transferred from the driver to the load. This study proposes a straightforward method for determining an absolute field calibration of a Radio Ear B71 bone driver, found by measuring the electrical input impedance of the transducer loaded by known masses. This absolute calibration is based upon a circuit model of the driver, describing it with three frequency-dependent parameters. Once these three parameters are known, measurements of the driver input voltage and current may be used to determine arbitrary mechanical load impedances (such as the in situ mastoid impedance), and thus the frequency dependence of the transmitted energy. The results of the proposed calibration method are validated by comparison with direct mechanical measurements using specialized equipment not available in the clinic, and a refined bone driver circuit model is proposed to better capture the observed behaviors.
在使用骨振器换能器进行临床测量时，骨驱动器的能量传递取决于驱动器与负载（人乳突或其他）之间的阻抗匹配，驱动器将施加到负载上。当前的临床校准方法无法量化这种阻抗失配，因此无法考虑从驱动器传递到负载的能量的个体间差异。本研究提出了一种确定 Radio Ear B71 骨驱动器绝对场校准的简单方法，通过测量加载已知质量的换能器的电输入阻抗来实现。这种绝对校准基于驱动器的电路模型，用三个频率相关参数来描述它。一旦这三个参数已知，就可以使用驱动器输入电压和电流的测量值来确定任意机械负载阻抗（例如原位乳突阻抗），从而确定传输能量的频率依赖性。所提出的校准方法的结果通过与使用临床不可用的专用设备进行的直接机械测量进行比较来验证，并提出了一种改进的骨驱动器电路模型来更好地捕捉观察到的行为。
