Double Tonguing

What it is: Articulating two notes per syllable pair — alternating "tu-ku tu-ku" — so the back of the tongue handles every other note. This effectively doubles the maximum articulation speed.

What it sounds like: Crisp, rapid-fire repeated notes. Used for passagework that's too fast for Single Tonguing.

When to use it: Fast running passages, machine-gun repeated notes, virtuosic scale runs. Standard on flute, possible on clarinet/oboe/bassoon (harder, less idiomatic), and fundamental to all brass technique.

Tip: Beginners often have an audible tonal difference between the "tu" and "ku" — the front-tongued "tu" is brighter, the back-tongued "ku" is duller. Pros equalize them. When writing for student-level players, don't expose double-tongued passages — bury them in the texture.