Influence of the fluctuations of the control pressure on the sound production in flute-like instruments

Abstract

International audienceIn flutes and flue organ pipes, the supply pressure is often considered as a control parameter at time scales lower than the acoustic time scales. For instance, the typical time of a rise of pressure represents an objective descriptor to analyse attacks (typical time about 20 ms for fast attacks). It has been observed that the supply pressure is also prone to oscillate at time scales of the order of the acoustic time scales. This is due to the acoustic coupling between the instrument and the pressure reservoir. The present work investigates the influence of such a coupling on the sound production, and its pertinence from a musical point a view. In other words, can the ability of a musician (or an instrument maker) to control this coupling be regarded as a control parameter of the sound production? This paper presents a preliminary experimental study focused on the effects of a pulsating supply pressure on the sound production. The fluctuations of the supply pressure are forced by using a loudspeaker within an artificial mouth. Different effects -- such as modifications of the spectral enhancement, shifts in the regime change thresholds or changes in the transients --, resulting from different supply and "coupling" conditions are presented