Broadband noise generated by a fan is studied numerically using a novel variant of the DES the Improved Delayed Detached Eddy Simulation (IDDES). The IDDES is used together with the Chimera grid overset technique for the independent griding of the rotor, stator and channel and a highly parallel sliding mesh interface suitable for huge simulations. The reference experiment is the DLR Fan Rig within the EC founded project FLOCON. It has a rotor blade count of 24 with 32 stator vanes. The rotational tip Mach number is M = 0.220 at nominal loading with a rotor gap height of 2.4 mm. The objective of the present investigation is to directly simulate the fan rig tip leakage vortex broadband noise using the IDDES. The LES focus region is the tip area including the boundary layer at the casing wall downstream towards the stator vanes. In the remaining domain we use coarser grids suitable for URANS. To capture the effect of the interaction between the rotor blades and stator vanes, a full periodic setup with 3 rotor blades and 4 stator vanes is investigated with the total number of 55 million cells on 600 CPUs. The IDDES approach is designed to extend the LES region of the original DES approach (hybrid RANS/LES) from Spalart et. al. (1997) to the turbulent boundary layer, as proposed first by Travin et. al. in 2006. The non-zonal blending occures therefore inside the boundary layer the RANS model acts as a wall model for the LES. The actual work shows the capabilities of this novel approach for the simulation of broadband noise in turbomachines.