Player's Lips Research Articles

Gagaku, Ensemble OnoTeruhisa Fukuda, maître de shakuhachi. Offrande musicale

Gagaku, Ensemble OnoTeruhisa Fukuda, maître de shakuhachi. Offrande musicale

Navier-Stokes-based model of the clarinet.

A model of a single reed instrument is studied in which the reed is described as an Euler-Bernoulli beam, and the air flow through the instrument is calculated using the Navier-Stokes equations. The hypothetical instrument resembles a clarinet, but is smaller than a real clarinet to keep the numerical modeling feasible on available supercomputers. This article explores the conditions under which the frequency of the reed oscillations and the emitted sound are determined by the resonant frequency of the bore of the instrument. The effect of the contact between the reed and the player's lips is also studied, and quantitative results for the air density and pressure in the mouthpiece and throughout the instrument bore are also presented.

Force on the lips of a trumpet player.

When modeling a brass instrument such as the trumpet, an estimate of the pressure at the player's lips is essential, since the resulting force drives the oscillations of the lips which are needed to produce a musical tone. In most work to date, the calculation of the force on the lips has relied on values of the pressure derived from the Bernoulli equation, even though that relation assumes steady flow in contrast to the pulsating flow caused by vibrations of the lips. This paper uses a quantitative application of the Navier-Stokes equations to calculate the flow through a model of vibrating lips attached to a toy model of the trumpet. The results are used to explore when the Bernoulli equation can and cannot be used. The Bernoulli equation is found to fail badly during significant portions of each oscillation cycle of the lips. The reasons for this breakdown are elucidated.

Physics-based resynthesis of clarinet performance using numerical optimization

The functioning of musical instruments has been an active area of research since the beginning of the last century, using both theoretical approaches and experimental measurements. Regarding wind instruments, the subtleties of embouchure control are of particular interest, since the actions of the player's lips and tongue evade direct measurement. One approach towards analyzing such actions is by extracting relevant information from signals that allow non-intrusive measurements, such as the blowing pressure, the mouthpiece pressure and the reed bending [Pàmies-Vilà et al. (2018) Frontiers in Psychology 9: 617]. Alternatively, it is possible to formulate a physical model of the player-instrument interaction and estimate the actions of the player while resynthesizing the oscillations of the instrument [Chatziioannou et al. (2012) Acta Acustica united with Acustica 98(4): 629–639]. This work presents such an attempt based on measurements carried out on expert clarinet players. An excerpt of Weber's clarinet concerto No. 2 is performed by the players and resynthesized using a refined physical model taking embouchure effects into account. Using inverse modeling, the underlying model parameters are being tracked in order to extract information on the physical phenomena that take place at the excitation mechanism.

Physical modeling of a conical lip reed instrument.

A model of a brass instrument is described in which the air flow and pressure inside the instrument are computed with the Navier-Stokes equations and the motion of the player's lips are described using the swinging lip model of Adachi and Sato [J. Acoust. Soc. Am. 99, 1200-1209 (1996)]. Using the Navier-Stokes equations to treat the air motion allows the calculation of the spatial variations and time dependences of the pressure and velocity near the lips, which has not been possible with previous modeling approaches. Detailed results for these quantities and for the lip motion are presented, and compared with the results of previous modeling of lip reed instruments and with available experimental results. Shortcomings are found in previous treatments of the aerodynamic force on the lips, and the implications of this result for first-principles modeling of brass instruments are discussed.

Simulation studies of the flute

Simulations of the transverse flute using direct numerical solutions of the Navier-Stokes equations are described. Constructing a numerical model of the instrument itself is straightforward, but making a semi-realistic model of the player's lips is more challenging. One solution to this problem is described and used to explore the kinds of tones that are possible. Conditions are found for which the model produces a well-behaved musical tone for a range of blowing speeds. When the blowing speed is increased beyond this range the behavior becomes complex and is appears to be chaotic. An analysis of this behavior in terms of the sensitivity to initial conditions and a route to chaos involving Hopf bifurcations is described. The relevance of these results to real instruments played by real players is also discussed. [Research supported by NSF grant PHY1513273.]

Energy Balanced Model of a Jet Interacting With a Brass Player's Lip

In most physical models of brass instruments, the air jet (located at the exciter) is governed by an equation of Bernoulli-type for which basic, unsteady or lossy versions are available. The non-linearity introduced by such model is known to be of utmost importance for wind instruments: it is responsible for self-oscillations when fed by a power source. However, this type of model is unable to make the air flow work at a mobile boundary (lip) as it does not account for any transverse component (the vertical dimension during normal brass playing) in the velocity field. In this sense, it is ill adapted to properly address the power exchanges between the jet and the lips. This paper addresses the following twofold issue. The first issue is the derivation of an air flow model in the unsteady case that restores the fundamental property of passivity at boundaries. The second issue is the test of its relevance in self-oscillating contexts, based on passive-guaranteed simulations of a simplified complete instrument. To make the air flow model as simple as possible, its derivation relies on standard Bernoulli assumptions (irrotational, incompressible flow without loss) except for the boundary conditions at the wall. It is derived in two steps. First, we solve the 2D velocity and pressure fields of the Euler equation for boundary conditions that are adapted to a moving lip. Second, we derive a macroscopic model based on averaged velocities and pressures. This yields a finite dimensional differential system which proves to be equivalent to the original one, in the sense that both the velocity and the pressure fields can be recovered from the macroscopic variables. Moreover, it preserves the power balance of the original physical system. Then, a simplified model of an instrument is built by connecting this system to a lip (mass-spring-damper) and to a conservative straight pipe with an ideally dissipative termination. Passivity is fulfilled and the complete power balance is explicitly encoded by recasting the model into the “Port-Hamiltonian formulation”. A numerical scheme that preserves passivity is proposed to simulate the complete system supplied by an ideal air pressure generator. Finally, results are compared with those based on the standard Bernoulli equation.

The effect of nearby timpani strokes on horn playing

Horn players have observed that timpani strokes can interfere disruptively with their playing, especially when they are seated close to the timpani. Measuring the horn's transfer function in the bell-to-mouthpiece direction reveals that the horn behaves as an acoustic impedance matching device, capable of transmitting waves with pressure gains of at least 20 dB near horn playing resonances. During moderate to loud timpani strokes, the horn transmits an overall impulse gain response of at least 16 dB from the bell to the mouthpiece, while evidence of non-linear bore propagation can be observed for louder strokes. If the timpani is tuned near a horn resonance, as is usually the case, further bore resonance interactions may be observed leading to gains of ∼26 dB from bell to mouthpiece. Finally, measurements of horn playing made under conditions approximating playing reveal that timpani strokes sounding near the horn bell are capable of disrupting horn playing by affecting the amplitude, periodicity, and frequency of the pressure signal generated at the horn player's lips.

How can we deduce playing frequencies from measured resonance frequencies for trumpets?

Lip-type valve (“striking outwards” type) is responsible for sound production for brass instruments. The operation of the valve is controlled by feedback from a passive resonator. The purpose of this study is to compare experimentally how far the resonance frequencies of instrument, taken from their input impedance (which does not involve the intervention of the player's lips) are able to give informations about the playing frequencies. A family of three trumpets made from a basic instrument for which the lead pipe will be slightly modified for each model, were considered for the experiment. Four expert musicians were asked to play the first five playable notes, for four different fingerings and for three nuances. This exercise was repeated three times. All these notes allow to make a quantitative assessment of the relation between the resonance frequencies and the playing frequencies, using in particular statistical methods. Several results will be presented: the influence of the player on the overall intonation, the effect of nuances on the pitch and the relation between small changes of geometry and playing frequencies. Functions made from the input impedance, such as the « sum function » proposed by Wogram, do not bring more relevant informations than the input impedance itself.

The soft-source impedance of the lip-reed: Experimental measurements and computational simulation

Most theoretical descriptions of the brass instrument lip-reed consider the acoustical condition at the lips to be a closed, rigid termination, corresponding to a unitary reflectance. This assumption is carried through to many computational models as well. In reality, the protrusion of the player's lips into the mouthpiece causes a periodic shortening/extension of the acoustical tube downstream, an effect sometimes but not always incorporated into such models. Of interest here is the absorption properties of the lip termination, the so-called “soft source impedance.” This provides a further modification to the boundary condition at the lips, since the soft, deformable nature of the lips are likely to cause some extra damping of the acoustic standing wave. Measurements are presented to demonstrate this damping effect using an artificial mouth. This is achieved through measurements of the lip reflectance from downstream of the lips, from where it is shown that the reflectance shows a dip at the peak absorbance frequency of the lips. The frequency of the absorbance is shown to vary as the lip parameters are changed. A simple computational model is described to account for the effect.

Open Areas of Vibrating Lips in Trombone Playing

In brass instruments the player's lips are used as a control valve that allows an oscillating flow of air into the instrument. The behaviour of this valve, the lip-reed, is determined by both the pressure difference across the lips and the open area between the lips. Computer simulations of brass instrument playing frequently represent the lips as an oscillating system with one degree of freedom, representing the height of the lip opening. This study aims to provide experimental evidence to determine values of an exponential coefficient q defining the area-height function for the lips of trombone players. A high speed digital video camera and transparent mouthpiece have been used to produce detailed images of the motion of the vibrating lips of a range of musicians and an artificial mouth over a large set of playing frequencies and sound levels. These images are analysed to investigate how the open area varies as a function of the height between the lips.

Motion of the lips of brass players during extremely loud playing

When a brass instrument is played loudly, the energy level of the higher harmonics increases dramatically. The generally accepted explanation for this is non-linear steepening of the wavefront and generation of shock waves within the instrument bore. However, it has also been suggested that changes in the player's lip vibration could play a role in generating this "brassy" sound. To test this hypothesis, the dependence of lip opening-area on time has been measured for different dynamic levels in trombones and horns. Results suggest that the behavior of the open area does not change dramatically when the instrument enters the brassy regime.

Vocal tract resonances in speech, singing, and playing musical instruments.

IN BOTH THE VOICE AND MUSICAL WIND INSTRUMENTS, A VALVE (VOCAL FOLDS, LIPS, OR REED) LIES BETWEEN AN UPSTREAM AND DOWNSTREAM DUCT: trachea and vocal tract for the voice; vocal tract and bore for the instrument. Examining the structural similarities and functional differences gives insight into their operation and the duct-valve interactions. In speech and singing, vocal tract resonances usually determine the spectral envelope and usually have a smaller influence on the operating frequency. The resonances are important not only for the phonemic information they produce, but also because of their contribution to voice timbre, loudness, and efficiency. The role of the tract resonances is usually different in brass and some woodwind instruments, where they modify and to some extent compete or collaborate with resonances of the instrument to control the vibration of a reed or the player's lips, andor the spectrum of air flow into the instrument. We give a brief overview of oscillator mechanisms and vocal tract acoustics. We discuss recent and current research on how the acoustical resonances of the vocal tract are involved in singing and the playing of musical wind instruments. Finally, we compare techniques used in determining tract resonances and suggest some future developments.

Lip control of brass instruments

Brass instruments are frequently described in the acoustics literature as lip reed instruments, emphasising the fact that the sounding mechanism of this instrumental class is flow modulation by the vibration of the player's lips. As well as providing the source of sound, the lips act as the major interface through which the performer controls the intonation, dynamics, articulation and timbre of the performance. Indeed, on instruments such as the natural trumpet and the alphorn, the player's lips form the only control interface. This paper reviews recent studies which have examined the vibrational properties of brass players' lips, the types of motion which they undergo when playing different instruments, and the nature of the interaction between the lips and the instrument. It also considers the extent to which current physical models of the lips are capable of encompassing these control processes.

Gesture synthesis: basic control of a flute physical model

In the flute family, the oscillation is due to the instability of a jet at the output of a channel coupled with an acoustic resonator. Recent physical models allows to simulate the behavior of the complete instrument, but we still lack a convincing way to drive them. The simulation of the isolated instrument must be completed with a modelization of the control exerted by the flutist. Depending of the instrument of the flute family, the number and type of control parameters are differents. For example, in a recorder the player blows inside a fixed channel built by the instrument maker and in the case of the transverse flute, the channel is shaped by the player's lips during the playing. This paper presents a simple model of flute player, based on measurements carried on instrumentalists playing on a recorder or a transverse flute. The model is generating the basic features of the instrument control in order to produce given pitches and dynamics. The coupling with a flute physical model allows to study its validity.

Vocal tract resonances and the sound of the Australian didjeridu (yidaki) I. Experiment

The didjeridu, or yidaki, is a simple tube about 1.5 m long, played with the lips, as in a tuba, but mostly producing just a tonal, rhythmic drone sound. The acoustic impedance spectra of performers' vocal tracts were measured while they played and compared with the radiated sound spectra. When the tongue is close to the hard palate, the vocal tract impedance has several maxima in the range 1-3 kHz. These maxima, if sufficiently large, produce minima in the spectral envelope of the sound because the corresponding frequency components of acoustic current in the flow entering the instrument are small. In the ranges between the impedance maxima, the lower impedance of the tract allows relatively large acoustic current components that correspond to strong formants in the radiated sound. Broad, weak formants can also be observed when groups of even or odd harmonics coincide with bore resonances. Schlieren photographs of the jet entering the instrument and high speed video images of the player's lips show that the lips are closed for about half of each cycle, thus generating high levels of upper harmonics of the lip frequency. Examples of the spectra of "circular breathing" and combined playing and vocalization are shown.

Vocal tract resonances and the sound of the Australian didjeridu (yidaki) II. Theory

The didjeridu (didgeridoo) or yidaki of the Australian Aboriginal people consists of the narrow trunk of a small Eucalypt tree that has been hollowed out by the action of termites, cut to a length of about 1.5 m, smoothed, and decorated. It is lip-blown like a trumpet and produces a simple drone in the frequency range 55 to 80 Hz. Interest arises from the fact that a skilled player can make a very wide variety of sounds with formants rather like those of human vowels, and can also produce additional complex sounds by adding vocalization. An outline is given of the way in which the whole system can be analyzed using the harmonic-balance technique, but a simpler approach with lip motion assumed shows easily that upper harmonics of the drone with frequencies lying close to impedance maxima of the vocal tract are suppressed, so that formant bands appear near impedance minima of the vocal tract. This agrees with experimental findings. Simultaneous vibration of the player's lips and vocal folds is shown to generate multiple sum and difference tones, and can be used to produce subharmonics of the drone. A brief discussion is given of player preference of particular bore profiles.

Bioengineering. Identification of Control Parameters for Brass Player's Embouchure by Measuring Contact Pressure on the Teeth Buccal Surface.

For the technical improvement for brass instrument players it is important to obtain the detailed control parameters for embouchure building. While many investigators have reported the preliminary data on the muscle behavior, the precise aspects are unrevealed so far. The purpose of the present paper is to study dynamic perioral muscle behavior of French horn players and to investigate their lip valve function by measuring the contact pressure on teeth buccal surface during playing. It was shown from the experimental results that the advanced players contracted depressor angulioris and levator angulioris especially for high tone playing. It is considered that the combined contraction by these muscles contributes to forming smaller lip aperture being suitable to produce higher tones. Inversely a strong contraction of m. buccinator, which is widely believed to work to give hard tension to player's lip, was observed insignificantly in the advanced players.

Nonlinear dynamics of musical reed and brass wind instruments

A musical wind instrument transforms a constant pressure input from the player's mouth into a fluctuating pressure output in the form of a radiating sound wave. In reed woodwind and brass instruments, this transformation is achieved through a nonlinear coupling between two vibrating systems: the flow control valve formed by the mechanical reed or the lips of the player, and the air column contained by the pipe. Although the basic physics of reed wind instruments was developed by Helmholtz in the nineteenth century, the application of ideas from the modern theory of nonlinear dynamics has led to recent advances in our understanding of some musically important features of wind instrument behaviour. As a first step, the nonlinear aspects of the musical oscillator can be considered to be concentrated in the flow control valve; the air column can be treated as a linear vibrating system, with a set of natural modes of vibration corresponding to the standing waves in the pipe. Recent models based on these assumptions have had reasonable success in predicting the threshold blowing pressure and sounding frequency of a clarinet, as well as explaining at least qualitatively the way in which the timbre of the sound varies with blowing pressure. The situation is more complicated for brass instruments, in which the player's lips provide the flow valve. Experiments using artificial lips have been important in permitting systematic studies of the coupling between lips and air column; the detailed nature of this coupling is still not fully understood. In addition, the assumption of linearity in the air column vibratory system sometimes breaks down for brass instruments. Nonlinear effects in the propagation of high amplitude sound waves can lead to the development of shock waves in trumpets and trombones, with important musical consequences.

Acoustical behavior of brass player’s lips

The controversial problem of whether a brass player's lip movements are best modeled as outward striking or as upward striking is approached by measuring the phase difference between mouthpiece pressure and lip displacement. In analogy with the phase of the input impedance to a resonant system, the negative/positive value of this phase difference suggests an outward-striking/upward-striking oscillation. On the basis of this speculation, the experimental results revealed the following: (1) Large lip-driven pipes support both outward-striking and upward-striking oscillations because of the lip's high flexibility in the absence of a mouthpiece; (2) mouthpiece-nonresonant tube systems almost support the outward-striking oscillation over a wide frequency range; (3) mouthpiece-resonant tube systems totally support the outward-striking oscillation; (4) the French horn and trumpet exhibit the outward-striking oscillation for the lowest mode and the upward-striking oscillation for higher modes. The oscillation transition in brass instruments, which corresponds well to the change of mouthpiece pressure waveform from a low-pitch, nonsinusoidal one to a higher-pitch, more sinusoidal one, depends mainly on the nonlinear acoustic impedance of the lip opening. If its magnitude is negligible, the cavity coupling between the mouthpiece cup and player's mouth yields a capacitive input impedance that favors the outward-striking oscillation; if its magnitude is significant, the cavity decoupling is likely to yield an inertive input impedance that favors the upward-striking oscillation. Since both the time-varying Bernoulli pressure at the lip opening and the area receiving this pressure are generally apt to increase as the blowing pressure increases, the upward-striking oscillation tends to dominate higher mode tones in brass instruments.