Spatial map of travel-time shifts Δ_QSτ of p₁ modes through the reference sunspot model. The SLiM code numerically computes the waveform as a function of time through the reference sunspot model. The color bar indicates the travel-time shift in seconds. The ellipse encloses the region for which the spatial average of the travel-time shift (denoted with symbols ⟨  ⟩) is computed. The gray (black) circle indicates the penumbra (umbra) of the sunspot.