The invention presents a design of optimum edges for antennas of loudspeakers, microphones, hydro-speakers, hydro-phones, brass and wind instruments, and ultrasonic transducers. These edges have a serrated-roll shape, and enhance the acoustical field strength uniformity. Loudspeakers, hydro-speakers, and ultrasonic transducers will become more effective in radiating acoustical power. The quality of these apparatuses are enriched. The musical tone emitted by loudspeakers, brass and wind instruments becomes more smooth, mellow, rich, clean, and elegant.