Analytical resonance conditions for oscillation modes in stars are very helpful to examine their frequency spectra and make the link with their internal properties. In general, modes propagate in several resonant cavities, coupled with each other by intermediate evanescent regions. Moreover, local sharp variations in the stellar structure can perturb the frequency pattern, the so-called glitches. Difficulties then can occur in the interpretation of the data when the frequency spectrum results from different contributions, whether coupling through an evanescent region or glitches. In this talk, we will introduce a general resonance condition that can account for a multitude of resonant cavities and glitches. As an illustration, this new formulation will be used to predict the oscillation frequencies in some peculiar cases. Its potential to disentangle the contribution of each ingredient in spectra will be underlined.