Broadband microphones

Broadband microphones (from the audible range to ultrasound), which can be achieved in a converter using the piezoelectric properties 33 in the thickness direction, have aheady been applied as transducer elements in an airborne ultrasound transducer (Yasuno et al. 2010). Application to ultrasonic probes for medical use is also expected. 

Seismic sensor is a kind of microphone which converts the ground movements into electric signal. Modem sensors which are used for volcano surveys are three-component broadband instmments which allow recording oscillations of more than 30-40 s period (see also Principles... 

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