The measured upstream impedance for clarinet performance and its role in sound production

Abstract

The performer's use of the airways, including the mouth, tongue, throat, and lungs, during clarinet performance was studied by measuring the airway resonances. This research tested the theory that the performer tunes airway resonances to the harmonic frequencies of a tone, producing a more stable pressure oscillation. The resonances were determined from the upstream (airway) impedance, which was measured for clarinet performance directly using a one-microphone method and indirectly using the linear continuity of flow equation, the measured downstream (instrument) impedance, and simultaneous measurements of the upstream and downstream pressures. The indirect method was verified for single, normal tones at low pressure levels in the clarion and altissimo registers. Chalumeau-register tones had greater uncertainty in the magnitude, and the phase was indeterminate.The airway resonances were examined during performance of several musical phenomena. Resonances were slighty stronger at piano dynamic levels, compared to forte, consistent with a decreased glottal opening at piano. A "closed throat" had resonances that were stronger and broader than an "open throat", which produced the better tone quality. The airways may have a role when playing clarion tones without the register key, although the reed resonance may also be involved. For tones with pitchbend, the performer created a strong airway resonance at the fundamental frequency. For multiphonics, the performer created an airway resonance at a frequency that was a simple linear combination of the instrument resonance frequencies, and adjustment of airways resonance frequencies produced different multiphonics with the same fingering. In musical excerpts, the performer tuned the airways to the first or second harmonic, but there were also a number of tones that did not have an airway resonance aligned with a harmonic. In addition, the airways were involved in crossing register breaks, and there were variations that indicated the performer's use of the airways depended on the musical context.In summary, the role of the airways in clarinet sound production is important, and more research is needed to fully understand the complex relationship between the performer's airways and the clarinet.