How do flutes produce sound from an airstream and a sharp edge?

Flutes produce sound through a process known as edge-tone generation. When a player directs a narrow stream of air against a sharp edge—such as the rim of a hole or an internal duct—the air stream is split.12

This action creates pressure changes that propagate down the instrument's air column. Reflections of these pressure variations then force the air stream to oscillate back and forth across the sharp edge, which reinforces the vibration at the resonant frequency of the tube. This interaction establishes standing waves within the air column, resulting in a clear, sustained pitch without the use of reeds.31

The time required for this steady-state oscillation to be established is referred to as the transient time of the instrument, which is a critical factor in how the human ear identifies different musical tones.3