The amplitude-frequency responses (AFRs) of ultrasonic oscillation transducers based on piezoelectric lithium iodate crystals of hexagonal modification and on magnetic soft ferrite powders are experimentally studied. The possibility to control the efficiency of magnetostriction powder transducers (MPTs) by variation in the value and orientation of the external magnetic field is shown. Results of measurements of the transformation efficiency for ferrites of various chemical compositions are presented.