This work aims at providing efficient numerical schemes for the simulation of diffraction by thin wires. Concerning electromagnetics, Holland model already provides precise results for such computations. However this method requires to calculate numerically the value of some unknown parameter. It appears that the correct value for this parameter substantially depends on the surrounding part of the mesh. For a model case of acoustic diffraction we propose an alternative method that does not require evaluating any parameter. We prove consistancy of such a method and show how it is related to the Holland method. This leads to a theoretical value of the Holland parameter.