The numerical performance and accuracy of different features of a wake interaction noise prediction model have been investigated by analysing the results obtained on the geometry of an existing contra-rotating fan. The source and propagation effects have been considered separately. First, the effect of modelling the source either with a parallel or with a skew gust formulation, based on Amiet's theory, has been investigated. The choice of the response function and its computation have been discussed. Then, the propagation formula has been modified to take into account the effect of the geometry of the blades on the retarded time of the emission.