Top blocks: normalised observed amplitude for P₁ (black curve) together with the theoretical monochromatic amplitudes (red curves) as calculated for a period P = 140.5 s and the atmospheric parameters determined for EC 01541−1409 for modes with degree of ℓ = 0−5 as indicated in the individual panels. Bottom blocks: the corresponding plots for the normalised monochromatic phase. Velocity fields were not included in our continuum phase calculations, which is why the observed phase jumps across spectral lines are not recovered by the models.