Here's how the slide changes the pitch of the notes:
1. Open Position: When the slide is fully extended (all the way out), it creates the longest possible path for the air to travel. This produces the lowest notes on the trombone.
2. Moving the slide in (towards the bell): As the slide is moved in, the path for the air becomes shorter. This raises the pitch of the note. Each successive position as you move the slide inwards corresponds to a higher note in the trombone's range.
3. Positions: Trombonists use specific hand positions to remember where to place the slide for different notes. The basic positions range from the 1st position (fully extended) to the 7th position (almost completely closed).
4. Combining slide positions and lip tension: In addition to the slide, trombone players also use their embouchure (lip tension and air speed) to adjust the pitch and produce specific notes. Certain notes may require slight adjustments to the embouchure in combination with the correct slide position.
5. Additional playing techniques: Experienced trombone players may also employ other techniques to change notes, such as fingering triggers or using extended slide positions beyond the 7th position.
By skillfully moving the slide and controlling their embouchure, trombonists can produce a wide range of notes and create beautiful melodies, harmonies, and solos.