Flows through the cavities takes place in many machines and devices. The most popular examples include: landing gear cavities, bomb hatches, open car windows or gaps in car bodies. Those examples relate to open flows. In addition, this type of flow occurs in many elements of a gas or steam turbine blade system such as labyrinth seals or rim seals applied between the stator and rotor disks of the turbine stage. In those cases the influence of the flow channel walls on the mechanism of generation and propagation of disturbances should be additionally considered. The flow over cavities is characterized by a strong flow field instabilities associated mainly with the formation of a vortex shedding in the inlet area and strong pressure pulsations which are the source of generated noise. The vortex path that is being formed is often characterized by large coherent structures. Their number directly affects the frequency of the generated acoustic wave. The presented research is a continuation of the authors' work on this type of flows. The aim of this paper is a detailed comparison between numerical and experimental research which will cover a wide range of flow conditions including two basic modes of cavity acoustic response along with the transition between these modes.