A stackable horn configured such that a plurality of substantially identical horns can be stacked to form an array. Each horn diminishes in interior area from a mouth to a throat thereof and is vertically taller and longitudinally deeper than it is wide. The horn or array may be secured to a support. In the array, the horns are similar or identical and are arranged side-by-side with a space in between or in abutting contact. An aperture is defined in the throat of each horn and a microphone is positioned within the throat of each horn in the array. The arrangement of horns in the array permits beamforming and as a result allows simultaneous detection, tracking, and identification of multiple targets. Listening distance is greatly increased by utilizing the horn or the array of horns.