Influence of wall vibrations on the behavior of a simplified wind instrument

Abstract

The issue of the influence of wall vibrations on the behavior of wind instruments is still under debate. The mechanisms of vibroacoustic couplings involved in these vibrations are difficult to investigate, as fluid-structure interactions are weak. Among these vibroacoustic interactions, the present study is focused on the coupling between the internal acoustic field and the mechanical behavior of the duct. For this purpose, a simplified single reed instrument consisting of a brass tube connected to a clarinet mouthpiece has been studied. A theoretical model of coupling between the plane inner acoustic wave and mechanical modes is developed and suggests that in order to obtain measurable effects of wall vibrations, the geometrical parameters of the studied tube have to be unusual compared to that of real instruments. For a slightly oval-shaped and very thin brass tube, it is shown theoretically and experimentally that a coupling between the inner plane acoustic wave and ovalling mechanical modes occurs and results in disturbances of the input impedance, which can slightly affect the tone color of the sound produced. It is concluded that the reported effects are unlikely to occur in real instruments except for some organ pipes.

Axial vibrations of brass wind instrument bells and their acoustical influence: Theory and simulations

“…The vibrational modes of brass wind instrument bells that have shapes with radial nodes, referred to here as elliptical modes, as well as similar modes that are present in the cylindrical tubes of woodwinds and organ pipes, have been studied by Nief et al [3][4][5] Elliptical modes are easily stimulated mechanically and during performance they can be stimulated by the vibration of the lips or by the vibrations of the air column. In either case the displacement of the metal at the antinodes of these modes can be significant.…”

Influence of wall vibrations on the sound of brass wind instruments

“…30 In spite of the fact that elliptic modes are easy to excite and usually exhibit large wall displacement amplitudes, their presence probably cannot explain all of the effects observed in the experiments described above.…”

“…30 Their work demonstrated that vibroacoustic coupling between the internal sound field and the walls of the instrument can occur; however, they concluded that these effects probably do not occur in musical instruments with the exception of some thin-walled organ pipes.…”

Considerations for the Design of Composite 3D Printed ‘Intermediate Level’ Trumpets

“…There is opposition to this belief with Smith (1978) stating that changing the material of the bell has 'no effect' on the sound. Moore's stance does seem to be the more popular, however, with the likes of Nief (2008) offering concurrent, albeit muddled, findings supporting the connection between wall vibrations and timbre. Kausel (2010) offered more robust support, claiming that, whilst the aetiology of the bell's impact is largely unknown, the findings of their research indicate that the 'majority of audible effects' are a direct result of the 'presence of strain oscillations' in the bell and their interaction with the air column of the instrument.…”