Profile of the Brunt-Väisäla frequency of the reference stellar structure, N. The extent of the convective core, the radiative interior, and the convective envelope are indicated in colour. The value of N was set to zero in the convective regions where N² < 0. The frequency limit where intermediate- and high-degree modes are unable to form in the Full model while visible in the EnvCZ model is indicated with the dotted grey line.