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Trombone/Legato Tongue
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A legato tongue is a very light tongue when playing trombone. It requires notes to be sustained their full duration, while having quick slide motion. Think of making a small indent in the wall of air passing into the trombone. You don't want to stop air flow or disrupt it but mearly show that it's not a slur being played. Playing staccato is kind of the opposite of legato tongue.