In a method of using an ultrasonic sensor comprising a two-dimensional array of ultrasonic transducers, a plurality of ultrasonic signals are transmitted according to a beamforming pattern at a position of the two-dimensional array. The beamforming pattern focuses the plurality of ultrasonic signals to location above the two-dimensional array, wherein the beamforming pattern identifies ultrasonic transducers of the two-dimensional array that are activated during transmission of the ultrasonic signals, and wherein at least some ultrasonic transducers of the beamforming pattern are phase delayed with respect to other ultrasonic transducers of the beamforming pattern. At least one reflected ultrasonic signal is received at the position according to a receive pattern, wherein the receive pattern identifies at least one ultrasonic transducers of the two-dimensional array that is activated during the receiving. The transmitting and the receiving are repeated at a plurality of positions of the two-dimensional array.