The trombone (; ) is a musical instrument in the brass family. Like all brass instruments, sound is produced when the player’s vibrating lips (embouchure) cause the air column inside the instrument to vibrate. Nearly all trombones have a telescoping slide mechanism that varies the length of the instrument to change the pitch. Many modern trombone models also utilize a rotary valve as a means to lower pitch of the instrument. Variants such as the valve trombone and superbone have three valves like those on the trumpet.