Embodiments of an adaptive ultrasound detecting system for a door assembly include an ultrasound transducer assembly mounted to the door assembly and a controller coupled to the ultrasound transducer assembly. The ultrasound transducer assembly is adapted to emit ultrasound detecting beams within the door path, and to trigger a detecting signal indicative of a body located within the door path when the body intersects at least one of the ultrasound detecting beams. The controller is adapted to receive information indicative of a position of the door along the path, and to vary emitting at least one detecting beam in accordance to the position of the door relative to the ultrasound detecting beams.