Nielsen V K
Electroencephalogr Clin Neurophysiol. 1975 Jun;38(6):647-52. doi: 10.1016/0013-4694(75)90167-4.
Accurate measurements of the vibration amplitude were Fig. 7. Reproducibility of double determinations of the vibratory perception threshold (log V2) in normal persons and uraemic patients. PH=pulp, big toe; MM=medial malleolus. Axes show read values in volts transformed into a log V2 scale. Full and strippled lines indicate mean and 95% confidence limits of expected variation (ref. Table II). Made possible by a piezo-electric transducer (accelerometer). With constant voltage to the vibrator slight compression of the tactor against the skin produced an increase in amplitude, similar to that seen with compression against a rubber diaphragm. Further compression had a variable effect on the vibration amplitude, depending on the nature of the underlying tissue (bone, soft tissue). An exact calibration of the vibration stimulus strength therefore appears impossible, and a comparison of the acuity of vibratory perception is invalidated by the different viscous-elastic protion amplitude and the square of the voltage, as seen for vibrations in air, was also demonstrable between independent measurements of the vibratory perception threshold (VPT) in the two terms. The intra- and interindividual variations in terms of the amplitude and the square of the voltage were of the same order. On a logarithmic scale the reproducibility of VPT was independent of the threshold stimulus strength.
振动幅度的精确测量是通过压电换能器（加速度计）实现的。给振动器施加恒定电压时，轻压触觉器使其紧贴皮肤会导致幅度增加，这与轻压橡胶隔膜时的情况类似。进一步按压对振动幅度的影响各不相同，这取决于深层组织（骨骼、软组织）的性质。因此，似乎无法对振动刺激强度进行精确校准，并且由于不同的粘弹性特性，振动感觉敏锐度的比较也变得无效。在空气中振动时，振动感觉阈值（VPT）的独立测量之间也证实了幅度与电压平方之间的关系。幅度和电压平方的个体内和个体间变化处于同一量级。在对数尺度上，VPT的可重复性与阈值刺激强度无关。图7显示了正常人和尿毒症患者振动感觉阈值（log V2）双次测定的可重复性。PH = 趾腹，大脚趾；MM = 内踝。坐标轴显示转换为log V2尺度的伏特读数。实线和虚线分别表示预期变化的平均值和95%置信限（参考表II）。
