When the vibrating column of air inside a woodwind or brass instrument is made longer, the pitch typically decreases. This is because a longer column of air vibrates at lower frequencies, which results in a lower pitch. In practical terms, for example, when a player extends the length of the instrument by using a slide (as in a trombone) or by opening more valves (as in a trumpet), it lengthens the air column, leading to a lower sound being produced. Conversely, shortening the air column (by using keys or valves to close off sections) raises the pitch.
When the vibrating column of air inside a woodwind or brass instrument is made longer the pitch
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