5th Congress of Alps-Adria Acoustics Association
12-14 September 2012, Petrćane, Croatia ______
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Alex Hofmann,*¹ Vasileios Chatziioannou,* Wilfried Kausel,* Werner Goebl,* Michael Weilguni,# Walter Smetana #
*Institute of Music Acoustics, University of Music and Performing Arts Vienna, Austria #Institute of Sensor and Actuator Systems, Vienna University of Technology, Austria
Abstract: Physical modelling based sound-synthesis requires physically meaningful parameters for controlling the model. Previous studies on modelling single-reed woodwind instruments have concentrated mostly on the influence of the pressure difference across the reed on the behavior of the reed oscillation. The interaction with the player's lips and the mouthpiece lay has also been taken into account. However, studies on the effect of the player's tongue are limited. Articulation on real saxophones is produced by tongue impulses to the reed. In portato playing the air pressure is held approximately constant by the player, while there are articular interactions of the tongue with the reed. In this study we aim to explain the influence of tonguing for tone production with single-reed woodwind instruments using experimental measurements in an attempt to model articulation in sound synthesis. During the experiments an alto-saxophone mouthpiece was attached to the saxophone neck and tones with different articulation were recorded. The mouthpiece pressure was measured using a microphone inserted into the mouthpiece and a strain gauge glued on a synthetic reed was used to track the reed bending. A damping effect of the tongue on the oscillating reed can be observed between two articulated tones and the release of the tongue affects the transient behavior of the instrument. An attempt is carried out to include the effect of the tongue control on articulation during a physical modelling application.
Key words: articulation, tongue, woodwind instruments, single-reed, physical modelling
1 INTRODUCTION In single-reed instruments tonguing is used to give tone- onsets a clean start (Bate, 1984; Liebman, 1989; Koch, Dynamics and articulation are two important parameters 1989). Articulation thereby describes the different in expressive music performance. In playing woodwind intensities and combinations which can be used to instruments, dynamics are controlled by the air stream combine two consecutive tones (Krautgartner, 1982; towards the mouthpiece. The influence of mouth-pressure Abeles, 1973). Goolsby (1997) measured that expert on the reed oscillation has been studied intensively by teachers spend 21% of band rehearsal time on instructions musical acousticians for saxophone and clarinet (see of articulation. Concepts of how to teach woodwind historical overview given by Nederveen, 1998). Based on articulation are intensively discussed in music education these findings physical models for steady-state sounds (Sullivan, 2006). were built. Liebman describes the technique of tonguing for Human classification of musical instruments depends saxophone players as follows: "it is the front portion of the highly on the attack phase of the sound, especially when tongue containing muscle tissue which flaps upward instruments are played in high register (Reuter, 1995). stroking the reed" (p. 28). Furthermore he explains the resulting effect as "the reed's motion and sound are
HMA-02 Page 1 of 5 momentarily stopped. The actual sounding of the articulation comes with the release of the reed". One common form of articulation is portato playing. It is produced by soft tongue movements while the player's air- stream is held constant (Koch, 1989). For fast sequences sometimes the technique of double tonguing is used. Hereby instead of a second tongue impulse to the reed, "the hump portion abruptly rises up striking the roof of the oral cavity which in turn stops the air flow from the larynx" (Liebman, 1989, p. 31). Liebman describes the sounding effect as less effective on saxophone than on the flute, but useful. We see that tonguing is an important part of musical training and conclude that tonguing-based articulation is essential to expressive music performance $8@?76!32!!A<:BC76:!D%E!9C?;F586G6!H8;F!98G7C5FC:6! on woodwind instruments. <;;
!""# !E23!!+6GC7B6B!B<;< Reed bending was measured on a synthetic saxophone Our measurements show reed bending and inner reed. A strain gauge (2 mm, 120 Ohm) was glued on the mouthpiece pressure under human performance condition. upper side of the reed to avoid lip contact. The sensor was placed in the center of the reed with a distance of 4 mm to 450"'6"# 0.3&780 #*'.&3 0)*&# -')#*/+.)& the tip (Fig. 1). In steady-state sound production the player's mouth- pressure bends the reed towards the mouthpiece, this $ %&&"' ()*+,-."/" -'"00*'" motion is additionally reinforced by the Bernoulli-force Inner mouthpiece pressure was measured by a small from the flow of air into the mouthpiece. condenser microphone (G.R.A.S. - 40DP, 26AS) inserted The bent reed reduces the tip opening, this lowers the air through a hole in the side of a Vandoren AL3 mouthpiece pressure in the mouthpiece. At a certain point the (Fig. 1). pressure which is build up in the mouthpiece turns the reed motion into the other direction and opens the mouthpiece tip. Constant air pressure from the player keeps this system oscillating.
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