The sousaphone is a brass instrument in the same family as the tuba. It is a type of tuba that is often used in marching bands and other outdoor musical ensembles. The sousaphone is shaped like a large, upright, bell-shaped tuba, but it has a smaller bore and a shorter, more compact sound. It is also typically played with a mouthpiece that is smaller than the mouthpiece used on a tuba. The sousaphone is known for its powerful, low, and resonant sound, which makes it ideal for outdoor performances.