A system for emitting an ultrasonic signal is provided. The system includes a first ultrasonic transducer and a second ultrasonic transducer. A plate of the first ultrasonic element faces a plate of the second ultrasonic element such that the plate of the first ultrasonic element is spaced apart from the plate of the second ultrasonic element by a gap. During operation of the first and second ultrasonic transducers, a uniform or omnidirectional ultrasonic signal may be emitted from the gap.