Trombone lip mechanics with inertive and compliant loads (“lipping up and down”)

Abstract

Trombonists normally play at a frequency slightly above a bore resonance. However, they can 'lip up and down' to frequencies further above the resonance (more compliant load) and below (inertive load). This was studied by determining the pressures, flows and acoustic impedance upstream and downstream and by analyzing high speed video of the lips. The range of lipping up and down is roughly symmetrical about the peak in bore impedance, rather than about the normal playing frequency. The acoustic flow into the instrument bore has two components; the flow through the lip aperture and the sweeping flow caused by the moving lips. Variations in the phases of each of these two components with respect to the mouthpiece pressure allow playing regimes loaded by bore impedances varying from compliant to inertive. In a simple model, this sweeping motion also allows the pressure difference across the lips to do work on the lips around a cycle. Its magnitude is typically about 20 times smaller than the work input to the instrument but of the same order as the maximum kinetic energy of the lips. In some cases, this sweeping work may therefore contribute most or all of the energy required for auto-oscillation.

A novel theory of Asian elephant high-frequency squeak production

“…The proposed mechanism can account for the observed intra- and interindividual acoustic variation in squeaks, which probably involves an idiosyncratic morphology along with muscle tensioning and pressure application techniques that set only parts of the lip mass in motion. Comparably, the frequency range of trombone players depends on the airflow and the volume changes of the lips upon aperture and contraction, which mainly maintain the oscillation [ 3 ]. Only advanced players can smoothly change the pitch (lip glissando) without jumping registers [ 3 ].…”

“…Comparably, the frequency range of trombone players depends on the airflow and the volume changes of the lips upon aperture and contraction, which mainly maintain the oscillation [ 3 ]. Only advanced players can smoothly change the pitch (lip glissando) without jumping registers [ 3 ]. Similar to vocal fold vibration [ 64 , 65 ], we suggest that the nonlinear phenomena in squeaks result from changes in applied air pressure and muscle tension in the closed lips.…”

“…What makes a brass trumpet sound is first and foremost the player pressing air from puffed out cheeks through closely tensed lips, inducing self-sustained lip oscillation. The lips are periodically forced open and closed by the air pressure and flow interplaying with myoelastic tissue properties—just as in vocal fold sound production [ 1 – 3 ]. The instrument then merely forms the spectral structure by resonating the sound produced by the vibration of the “buzzing lips.” This principle parallels the source-filter theory of vocal production [ 4 , 5 ], whose application beyond human speech fostered a growing understanding of how morphology and information content covary in animal signals [ 6 ].…”

Brass player’s mask parameters obtained by inverse method

“…In the literature, many models exist for the lips, with different degrees of complexity, either as a one degree of freedom oscillator (which is the most common), or a two degrees of freedom oscillator taking into account different polarities (cf. [3]), and models trying to come closer to the geometry of the opening section of vibrating lips (cf. [1], Sect.…”

‘Warming up’ a wind instrument: The time-dependent effects of exhaled air on the resonances of a trombone

“…By adjustment of blowing pressure and other control parameters that players would include in the term 'embouchure', players of modern brass instruments can 'lip up or down', i.e. raise or lower the pitch over a total range of roughly two semitones (Boutin et al, 2020) and thus can usually correct quickly for expected or heard errors in intonation. (Trombonists also have the slide available.)…”