HOW SOUND WORKS
How an accordion makes sound
The bellows move air. A key or button opens a path for it. A thin metal reed vibrates, producing a note.
How do the bellows make a sound? Let's follow the air and watch a reed vibrate!
The path from movement to sound
Move the bellows
Pushing sends air out; pulling draws air in. The bellows supply the airflow needed to play.
Open a valve
Pressing a key or button opens the valve for the selected note. Otherwise that air path stays closed.
Vibrate a reed
Air passing through makes a thin metal reed oscillate. The repeated changes in airflow become audible sound.
Follow the button action to the reed
Press a button to lift the pallet and open the air hole. Switch between the whole instrument, the button action and the reed close-up to follow the bellows and the vibrating reeds. Turquoise particles show airflow.
Press a button
Enable sound
Synthesised demonstration tones, not a recording of an instrument. Slow motion does not change the pitch.
The pallets are closed, so no air flows.
Drag to rotate, pinch to zoom. You can press the coloured buttons on the model.
A leather-and-felt pallet seals the air hole. The lever lifts it to open the route to the selected note.
C, D and E have different reed lengths and animation speeds. Dimensions and motion are illustrative, not measurements or real-time vibration.
A representative treble action with one reed pair per note. Parts are exposed and reed motion is slowed and enlarged for observation. Actual construction and button layouts vary.
Both actions are needed
Key only
The valve opens, but without moving the bellows there is no sustained airflow.
Bellows only
Air moves, but a closed valve prevents it from reaching the selected reed.
Key and bellows
Air passes through the open path and the selected reed sounds.
Push and pull
Air changes direction, so different reeds work on push and pull. Many piano accordions play the same pitch from one key in either direction. Some button accordions and Anglo concertinas play different pitches.
Pitch and volume
Pitch depends mainly on how fast the selected reed vibrates. Longer reeds generally sound lower; shorter ones sound higher. Bellows movement changes airflow, affecting loudness and how a note begins.
What does the air button do?
It lets air enter or leave without selecting a sounding reed, so the player can reposition the bellows.