The sousaphone is a brass instrument in the tuba family. Created around 1893 by J. W. Pepper at the direction of American bandleader John Philip Sousa, it was designed to be easier to play than the concert tuba while standing or marching, as well as to carry the sound of the instrument above the heads of the band. Like the tuba, sound is produced by moving air past the lips, causing them to vibrate or "buzz" into a large cupped mouthpiece. Unlike the tuba, the instrument is bent in a circle to fit around the body of the musician; it ends in a large, flaring bell that is pointed forward, projecting the sound ahead of the player. Because of the ease of carrying and the direction of sound, it is widely employed in marching bands, as well as various other musical genres. Sousaphones were originally made of brass. Beginning in the mid-20th century, some sousaphones have also been made of lighter materials such as fiberglass & plastic.

A brass instrument is a musical instrument that produces sound by sympathetic vibration of air in a tubular resonator in sympathy with the vibration of the player's lips. Brass instruments are also called labrosones or labrophones, from Latin and Greek elements meaning 'lip' and 'sound'.