Influence of the reed flow on the intonation of the clarinet

Abstract

The playing frequency of a reed instrument is generally mainly imposed by the resonator. Nevertheless, numerous other factors have an influence on the playing frequency. Among those, the volume velocity pulsated by the reed must be taken into account in the models as it lowers significantly the playing frequency. At first order, this volume velocity can be taken into account by adding an equivalent volume of about 1.cm3 at the entrance of the pipe. However, the concept of equivalent volume is theoretically only valid for linear vibrations i.e., for the clarinet: the non beating reed regime. In the beating regime, this volume is likely to vary quite a lot with the mouth pressure which can lead to intonation problems. In addition, this volume depends much on the reed opening, but experiments performed with an artificial mouth show that for usual openings (0.3-0.7mm) the intonation remains surprisingly stable. This suggests that the reed and mouthpiece makers know how to control this problem by a well chosen design of the lay. A counter-example is obtained by using a ClaripatchTM especially designed so that intonation is particularly difficult to control.