contour 9 which is likewise illustrated diagrammatically via the graph and narrows the flow cross section and which on account of the bernoulli effect leads first to an acceleration of the flow velocity in the x direction and after the overshooting of the region of the smallest flow cross section to an efficient flow deceleration with the result that the velocity profile experiences a higher gradient particularly at the forward stagnation point 6 see the dashed line owing to this local increase in the velocity gradient or else swirl gradient due to the convergent divergent flow routing the aerodynamic stability of the stagnation point 6 is increased without appreciable burner pressure losses in this case having to be taken into account the conduct of atmospheric combustion tests in each case with two structurally identical burners with and without contouring gives the result that premixing burners with the contouring according to exemplary embodiments of the invention have markedly lower pressure fluctuations than correspondingly conventionally designed premixing burners fig5 shows in this respect a graphical illustration along the x axis of which the flame temperature is indicated and along the y axis of which the magnitude of pressure fluctuations is indicated in the standardized illustration the line with the square markings corresponds to the operation of a premixing burner with the contouring according to an exemplary embodiment of the invention and the line having lozenges corresponds to a conventional premixing burner it is.