This paper concerns higher frequency vibrations of complex built-up structures, in particular, the issues raised by the gap between the recently-developed mid-frequency modelling approaches (e.g.the specialist hybrid methods [1-2]) and the well-established high-frequency modelling approaches (e.g.conventional Statistical Energy Analysis (SEA) [3]).A new concept of"near-high-frequency vibration" is thus firstly introduced to highlight the vibration problems for which neither mid-frequency hybrid modelling nor SEA modelling is directly applicable.