How do the valves work on a tuba?

The valves on a tuba function as mechanical devices that alter the length of the instrument's tubing, allowing the player to change the pitch of the notes produced. When a valve is pressed, it redirects the air flow through additional tubing, effectively lowering the pitch by increasing the volume of air the player must move. There are typically three or four valves on a tuba, each corresponding to different pitches. By combining different valve combinations, players can access a wider range of notes and improve tuning.