Profiles of the modified (solid lines) and usual (dashed lines) Brunt–Väisälä and Lamb frequencies (for ℓ = 1) as a function of radius in three 1.2 M_⊙ stellar models, corresponding to a subgiant star (SG), a young (YR) and an evolved (ER) red giant stars, respectively (see HR diagram in Fig. 3). The base of the convective zone (BCZ) and the hydrogen-burning shell (vertical dash-dotted line) are indicated. The blue horizontal strip symbolizes a 6Δν-wide frequency range around ν_max computed via Eqs. (6) and (7). Propagation occurs where 2πν ≲ (𝒩 and 𝒮₁) or 2πν ≳ (𝒩 and 𝒮₁), and evanescence otherwise.