Evolution of the zonal mode frequencies of stellar models with input parameters M = 6 M_⊙, X = 0.72, Z = 0.020, f_ov = 0.05, and D_mix = 1 cm² s⁻¹ (upper left panel), M = 8 M_⊙, X = 0.70, Z = 0.020, f_ov = 0.05, and D_mix = 100 cm² s⁻¹ (upper right panel), M = 6 M_⊙, X = 0.72, Z = 0.012, f_ov = 0.05, and D_mix = 1 cm² s⁻¹ (bottom left panel), M = 8 M_⊙, X = 0.70, Z = 0.020, f_ov = 0.01, and D_mix = 100 cm² s⁻¹ (bottom right panel). The panels show the zonal mode frequencies in the region of the measured frequencies of HD 170580, which are indicated as horizontal lines (dotted: l = 2, full: l = 1, dashed: unknown l). The model frequencies are coded as black circles: l = 1, n <  0, black plus signs: l = 2, n <  0, red triangles: l = 0, blue squares: l = 1, n ≥ 0, orange diamonds: l = 2, n ≥ 0.