We present a review of literature on aspects of sound production in a
clarinet which involve non-linearities of the flow in the instrument.
We discuss the flow in the reed channel, the contribution of turbulenc
e to the sound production, the vortex shedding at tone holes and the p
ipe termination and finally we discuss the non-linear wave deformation
in the pipe. Most of these effects can only be described qualitativel
y on the basis of existing theories and the experimental data are insu
fficient. Further research is welcome.