Acoustical interaction between vibrating lips, downstream air column, and upstream airways in trombone performance

Abstract

This paper presents experimental results on the acoustical influence of the vocal tract in trombone performance. The experimental approach makes use of measurements at the interface between the player and instrument, allowing a relative comparison between upstream airways and the downstream air column impedances, as well as an estimation of the phase of the impedance of the upstream and downstream systems. Measurements were conducted over the full traditional range of playing, during sustained tones with varying dynamic, as well as in special effects such as pitch bending. Subjects able to play over the full range demonstrated significant upstream influence in the higher register of the instrument. These players were categorized in two groups according to their ability to control the phase of the upstream impedance and their ability to generate powerful downstream acoustic energy. Sustained tones played with varying dynamics showed a general tendency of a decrease in vocal-tract support with increase in loudness. Although pitch bends did not involve significant upstream influence at f 0 , results suggest modification of the lip behavior during bending. Vocal-tract tuning at tone transitions was also investigated and found to potentially contribute to slur articulations.

In-Vitro and Numerical Investigations of the Influence of a Vocal-Tract Resonance on Lip Auto-Oscillations in Trombone Performance

“…These results are in agreement with previous in-vivo observations revealing an important influence of the vocal-tract in hte high register and at certain tone transitions [4].…”

“…Scaling parameter C is set so that the p u amplitude is of the same order of magnitude as p d , hence producing significant effect on the system. Such orders of magnitude of P u (f 0 )/P d (f 0 ) amplitude ratio are observed in trombone players in the higher register [4]. A quarter-period sinusoidal onset envelope is applied to the scaling factor so that the p u amplitude grows smoothly from zero to C when injected into the system.…”

“…In trombone performance, significant vocal-tract influence in the high register of the instrument was observed by measuring the ratio of the acoustic pressures upstream and downstream from the lips [4]. Furthermore, in the same study, the characteristics of the upstream and downstream impedances at the playing frequency could be derived by monitoring the phase of lip oscillations, and an early categorization of the upstream tuning strategy proposed during arpeggios.…”

“…In these experimental conditions, satisfactory performances of the PID controllers are empirically obtained by tuning the coefficients to the following values: K pa = K pp = 0.5, K ia = K ip = 0.06, and K da = K dp = 0. Because vocal-tract influence is expected in the higher register of the instrument as shown by measurements on human subjects [4], we try to focus on the highest tones that can be produced by the artificial player without active upstream feedback. Note that the performance of the proposed method is strongly dependent on the accuracy of the f 0 detection.…”

“…The study of the acoustical influence of upstream airways in brass instrument performance has been the object of growing interest in the last years [1,2,3,4]. In trombone performance, significant vocal-tract influence in the high register of the instrument was observed by measuring the ratio of the acoustic pressures upstream and downstream from the lips [4].…”