Shock Waves in Trombones

Abraham Hirschberg (1) , Joël Gilbert (1) , Régis Msallam (1) , A. P. J. Wijnands (1)

1 Equipe Acoustique instrumentale

Based on physical models of musical instruments and of the human voice, a new generation of sound syntesizers is born: virtual instruments. The models used for wind-instruments are simple feedback loops in uhich a non-linear sound source drives a linear,filter representing the pipe of the instrument. While very rewarding musical sounds have been obtained with these models, it has become obvious that some essential phenomena escape such a description. In particular the brightness of the sound generated by trombones is expected to be due to the essential non-linearity of the wave propagation in the pipe. At fortissimo levels this leads to shock wave formation observed in our experiments both from pressure measurements and flow visualization. A modest modification of the physical model could already take this phenomenon into account. The key idea is that the non-linear effect is essential for the transfer of sound from the source towards the listener, but can be ignored in a model of the generation of the pipe oscillations.

Mots clés: acoustique instrumentale; wind instruments; linear model

Domaines: Acoustique [physics.class-ph]; Vibrations [physics.class-ph]; Acoustique [physics.class-ph]; Vibrations [physics.class-ph]; Mécanique des solides [physics.class-ph]; Mécanique des structures [physics.class-ph]; Musique, musicologie et arts de la scène; Son [cs.SD]

Abraham Hirschberg, Joël Gilbert, Régis Msallam, A. P. J. Wijnands. Shock Waves in Trombones. Journal of the Acoustical Society of America, 1995, 99 (3), pp.1754-1758. ⟨hal-01105563⟩