Window Impedance of Recorder-Like Instruments

Sound production in recorder-like instruments occurs near an open end of the resonator. The impedance of this opening, named window and specific to flute-like instruments, acts both on the passive resonances and on the active behaviour. The geometry of the window is characterized by the presence of an edge needed for the sound source. This edge induces a significant enlargement of the section of the chimney associated with this opening. This study proposes a model of the frequency response of the window of recorder-like instruments inspired by previous works on open side holes. Predictions from this model are compared with measurements of a hand made recorder and to finite element simulations. Multiple geometrical conditions are simulated via finite elements and compared with the proposed model.