Volume 104, Issue 3, September 1998
Index of content:
- MUSIC AND MUSICAL INSTRUMENTS 
104(1998); http://dx.doi.org/10.1121/1.424374View Description Hide Description
In a toroidal bend in a cylindrical wind instrument, with the same cross section as the cylindrical part, the inertance for longitudinal waves is reduced. This induces a change in the resonance frequency. The magnitude of this change depends on the length and the sharpness of the bend and on its position in the sound field. A transition to a cylinder gives an additional inertance correction. The present study compares known results from literature and adds new facts, employing analytical and numerical methods. Possible causes of the discrepancies between measurements and theory as reported in the literature are considered. The theory was verified by measurements on some toroidal bends in between cylindrical tube pieces. Corrections were applied for diameter differences between the torus and the rest of the pipe system. Within experimental uncertainty, a satisfactory correspondence with theory was found. The results obtained in the present study determine which diameter reduction in the bend can compensate the effects of the bend on the tuning.
104(1998); http://dx.doi.org/10.1121/1.424375View Description Hide Description
Experimental results of a special artificial trombone player are presented: A mechanical device is a substitute for the musician. Wind instruments, and particularly the brass, are self-sustained oscillators. The oscillations are induced by a mechanical oscillator (the lips of the player) acting as a valve which modulates the flow. Measured mechanical parameters of the artificial buzzing lips for different “embouchures of the player” are presented, and analyzed in connection with the played frequencies obtained for the same “embouchures.” The results are obtained with two resonator systems (a mouthpiece alone and a trombone with its mouthpiece).
Numerical simulations of xylophones. II. Time-domain modeling of the resonator and of the radiated sound pressure104(1998); http://dx.doi.org/10.1121/1.424376View Description Hide Description
This paper presents a time-domain modeling for the sound pressure radiated by a xylophone and, more generally, by mallet percussion instruments such as the marimba and vibraphone, using finite difference methods. The time-domain model used for the one-dimensional (1-D) flexural vibrations of a nonuniform bar has been described in a previous paper by Chaigne and Doutaut [J. Acoust. Soc. Am. 101, 539–557 (1997)] and is now extended to the modeling of the sound-pressure field radiated by the bar coupled with a 1-D tubular resonator. The bar is viewed as a linear array of equivalent oscillating spheres. A fraction of the bar field excites the tubular resonator which, in turn, radiates sound with a certain delay. In the present model, the open end of the resonator is represented by an equivalent pulsating sphere. The total sound field is obtained by summing the respective contributions of the bar and tube. Particular care is given for defining a valid approximation of the radiation impedance, both in continuous and discrete time domain, on the basis of Kreiss’s theory. The model is successful in reproducing the main features of real instruments: sharp attack, tuning of the bar, directivity, tone color, and aftersound due to the bar-resonator coupling.
104(1998); http://dx.doi.org/10.1121/1.424377View Description Hide Description
The generation of sound by a pianosoundboard is investigated experimentally, through measurements of the sound pressure,p, and the soundboardvelocity, produced in response to a force applied at the bridge. Results for the ratio as a function of frequency, for forces applied perpendicular to the soundboard at different locations (i.e., driving points) on the bridge, are presented. At all locations, is largest at frequencies of order ∼1 kHz, and falls off below a few hundred Hz and above ∼5 kHz. A few results obtained with the force applied along the string direction (i.e., parallel to the plane of the soundboard) are also described. These results are compared and contrasted with previous experiments, and with theoretical expectations.