Radial velocity fluctuations v_r(r,θ₀,ϕ₀) as function of normalized radius for θ₀ = 35° (top) and θ₀ = 75° (bottom) represented for three consecutive instants (model ref). The longitude ϕ₀ = 150° is the same for both panels. The wavefronts move from the left to the right, allowing a radial phase velocity V_pr ≈ 2 × 10³ cm/s to be measured, independent of θ₀ and the same order of magnitude than the one calculated for a ray at ω₁ = 3 × 10^-3 mHz (see Fig. 14).