Variation in numerically determined cutoff frequency with height in the umbral model mMaltby permeated by a 3000 G magnetic field. Red asterisks show the measurements for the vertical magnetic field and blue asterisks those for a field inclination from the vertical of θ = 10°. Dashed blue line corresponds to the cutoff of the case with a vertical magnetic field multiplied by the cosine of the inclination θ = 10°.