Frequencies of HD 181231 observed with CoRoT (bottom panel) and growth rate of the modelled frequencies of low degree (ℓ ≤ 2) (first, third and fourth panels from the top) excited in a 5 M_⊙ star without mixing, calculated with the Tohoku code. The second panel from the top shows the azimuthal order m of the pulsation mode corresponding to the modelled frequencies in the third panel. Colours indicate the parity of the mode: even modes in solid red and odd modes in dashed blue lines. Stellar parameters used in the three models are indicated at the top of each panel.