Apparatus for picking up and analyzing emitted accoustic and ultrasonic signals by means of a piezoelectric pick up element connected to an amplifier with high input resistance, {HEAD ~ the output} of {TAIL ~ the amplifier} being connected for further evaluation to selective circuits and to an evaluation device 
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Apparatus for picking up and analyzing emitted accoustic and ultrasonic signals by means of a piezoelectric pick up element connected to an amplifier with high input resistance , { HEAD ~ the output } of { TAIL ~ the amplifier } being connected for further evaluation to selective circuits and to an evaluation device
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