臂带上的声波检测器带有五个压电悬臂，每一个可以检测某个特定频段的声音。
The acoustic detector in the armband contains five piezoelectric cantilevers, each weighted to respond to certain bands of sound frequencies.
超声波学。手持探头式多普勒胎儿心音检测器。性能要求和测量及报告方法。
Ultrasonics. hand - held probe doppler foetal heartbeat detectors. performance requirements and methods of measurement and reporting.
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