An audible signaling device uses one or more digital signal processors to modify the shape of a sound field to put high sound pressure levels only in a predetermined pattern, thus minimizing undesirable high volume levels in adjacent areas. Using digital signal processing techniques, and a plurality of high power amplifiers and loudspeakers mounted in an array on a moving vehicle, a carefully engineered sound field can be produced. The shape of this sound field is controlled by the frequencies amplitudes, and phases of the signals, as well as the characteristics and placements of the speakers in the array.