The fully-automated software 3PASS flex enables to simulate precisely background noise in different test rooms or in vehicle cabins in terms of level, frequency as well as spatial and temporal distribution in the area of the device under test. Application-specific microphone arrays (MSA I or MSA II) allow to record sound fields and to equalize the multi-channel background noise simulation system. The benefit of 3PASS flex: Equalization of the whole system is conducted fully-automated and digital.