The tuba is the largest and lowest-pitched musical instrument in the brass family. Like all brass instruments, sound is produced by moving air past the lips, causing them to vibrate or "buzz" into a large cupped mouthpiece. It is one of the most recent additions to the modern symphony orchestra, first appearing in the mid-19th century, when it largely replaced the ophicleide . Tuba is Latin for trumpet or horn. The horn referred to would most likely resemble what is known as a baroque trumpet
Components of the tuba
Mouthpiece: On brass instruments the mouthpiece is the part of the instrument placed on the player's lips. The mouthpiece is a simple circular opening that leads, via a semi-spherical or conical cavity, to the main body of the instrument.
Valves: Valves are used to change the length of tubing of a brass instrument allowing the player to reach the notes of various harmonic series. Each valve pressed diverts the air stream through additional tubing, individually or in conjunction with other valves.
Water Key: A water key is a valve or tap used to allow the drainage of accumulated fluid, consisting of condensed breath moisture, from musical instruments.