Brass instruments as we know them today

Since the time of Helmholtz, brass instrument models have treated the lips of the player as a pressure-controlled flow valve coupled to the instrument's resonating air column. This coupled system is a classic problem in non-linear dynamics. A simple one degree of freedom model of the lip valve has been shown to yield surprisingly realistic trumpet sounds, but many more subtle features of brass playing are not captured. Attention is currently focused on developing more sophisticated lip models, guided by experiments using artificial lip excitation systems and visualisations of human lip motion during playing. Modelling of the air column must take account of non-planar modes in rapidly flaring tubes, and non-linear propagation in longer instruments. Resonances of the player's windway can also be important, especially in wide bored instruments like the didjeridu.