Experimental Study of the Influence of the Mouth Geometry on Sound Production in a Recorder-like Instrument: Windway Length and Chamfers

The choice of the length and the geometry of recorder windways is an important design aspect as it influences the sound production by modifying the sensitivity of the jet to the acoustic field, thus modifying the jet motion. Shortening the channel seems to allow a better control of the instrument at low blowing pressures and makes the sound spectrum richer in high harmonics, but it also reduces considerably the pressure at which the instrument overblows. Adding chamfers to a long windway greatly stabilizes the system and gives the instrumentalist a wider dynamical playing range on a given mode of the pipe. Adding chamfers to a short windway doesn't help to stabilize the system.