High-power ultrasound or macrosonics is related to the high-intensity ultrasonic waves (1–10 W/cm2) applications that produce permanent changes in the treated medium. The propagation of high-intensity ultrasonic waves in media produces nonlinear effects associated with finite high amplitudes. All these physical effects can be employed to enhance processes that depend on the ultrasonic field irradiated into the medium. The successful application of this technology is related to the transducers and to the uniform distribution of acoustic fields within the processed medium. High-power ultrasonic waves are applied in wood processing for drying, defibering, cutting, plasticization, improvement of wood preservation.