Voltage peak in fibers causes changes of current circuit and crystal vibration, so that ultrasonic receiver (which currently is still the source that sends ultrasonic vibration) can detect echo.
纤维内的电压峰值引起电流回路和晶体震动的改变，这样使超声接收器（目前主要还是发出超声震动的源头）探测到的回声。