It has since long been known that the prediction of acoustic outcomes in corridor shaped rooms is not covered by classical room acoustic modelling. This case study aims to describe a case study of a corridor (length 26 meters) that was modified in terms of the amount of absorption in the ceiling, placement of absorption as well as the effect of diffusing/scattering objects.  An array of room acoustic measurements were used to asses the impact of these modifications. The results were analysed and systemised according to existing industry standards.