The aim of this paper is to present wave phenomena induced by the external action of ultrasound on porous wet materials subjected to drying. The purpose of these studies is to analyze the distribution of ultrasonic waves in such a complex medium and to discover the mechanism of ultrasonic interaction with both the solid skeleton and moisture in pores. The results obtained here should allow to state how ultrasonic waves are distributed in such material depending on ultrasonic frequency and on resistance between relative motion of the, constituents. This knowledge may help to explain enhancement of the drying mechanism by ultrasound, and in particular in biological products such as fruits and vegetables where a significant elevation of temperature is not required. (C) 2015 Elsevier Ltd. All rights reserved.