(under subclass 43) Subject matter wherein the selecting or attenuating characteristics are the opposite of similar characteristics of at least some part of the acoustic wave medium or system.
(1) Note. The filtering characteristics of the subject matter of this subclass may be the inverse of such characteristics of the acoustic wave medium or system as, for example, the transmitting transducer, the receiving transducer, recording equipment, connecting cables, the earth and transducer to earth coupling.