In the accompanying illustration of the head of a recorder, the wooden fipple plug (A), with a "ducted flue" windway above it in the mouthpiece of the instrument, channels the player's breath, so that it travels along the duct (B), called the "windway". Exiting from the windway, the breath is directed against a hard, bladed edge (C), called the "labium lip" or windcutter, producing a Bernoulli effect or siphon. The air flowing over the voicing mouth creates a flow-controlled valve, or "air reed."