G PHYSICS
G01 MEASURING; TESTING
G01N INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
G01N29/00 Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
G01N29/22 Details; , e.g. general constructional or apparatus details
G01N29/32 Arrangements for suppressing undesired influences, e.g. temperature or pressure variations; , compensating for signal noise