Abstract: An ultrasound applicator for heating, via an internal path, an ultrasound absorbent medium, includes an application head having a longitudinal axis and including at least one ultrasonic transducer having a planar emission face and an opposite face, a leakproof membrane which overlays and is spaced from the emission face, and which is transparent to ultrasound, and means for preventing propagation of ultrasound from the opposite face; means for remotely connecting the transducer to an electricity generator; and means for providing ultrasound coupling with the membrane. The planar emission face emits ultrasound waves through the membrane and in a direction that is substantially perpendicular to the emission face, such that the waves emitted are substantially planar and do not diverge in the vicinity of the transducer and the application head.