Parts and Sound
The trombone is an instrument made up of a mouthpiece, brass tubing, two slides and a bell. This instrument is part of the brass family, meaning it is a type of aerophone (an instrument played by the use of vibrations). Sound is produced when the player's vibrating lips cause the air in the tubing of the instrument to vibrate. This instrument produces sound with the help of three parts: the slide, the bell and your mouth (the embouchure).
Your lips form an embouchure, a shape which works with the mouthpiece. To make a higher pitched musical note, roll your lips under so that they are touching each other. To make a lower pitched note, form your lips into a pouting shape. These positions, along with air pressure, cause the lips to vibrate. The vibration is amplified through the tubing of the instrument. It is then projected out the bell to make sounds. The correct embouchure allows you to play the full range of notes without hurting or straining your muscles.
The slides of the trombone change the pitch. The main slide is a stationary long brass tube that encases the second slide. The second slide is a brass handle you extend down the main slide to change the pitch of the sound. The longer you extend the slide, the lower the pitch will be. There are seven positions at intervals along the slide. The first interval is located closest to the mouthpiece, and the last is towards the end of the slide. The reason this works is because you are extending the distance the vibrations must travel through the tubing to get to the bell, and this distance changes the pitch.
The structure of the brass instrument works together with your body to produce sounds. The instrument's functionality stems all the way from the cup-like mouthpiece, through the tubing and to the rounded bell. All it needs is the muscles of your lips, vibrations of air and the movement of the slide to produce music.