A new way to interpret the infrared spectra of transition aluminas in the OH as well as in the Al-O stretching spectral region is proposed. It takes into account the recent and key progresses made possible by different techniques of Al-27 high resolution NMR spectroscopy as well as by the application of molecular dynamics. The fundamental principle is the consideration of Al atom pairs. These Al atoms have all possible coordinations with respect to oxygen. A distinction between the bulk and surface phase's contributions is possible. The predictive power of this new approach is emphasized.