Comparison of acoustic variables in SSMs computed with different opacity tables, as reported in the legend of the left panel. Left panel: sound speed derivative and density as a function of the radius. Right panel: N, ∇T, μ, and the integral of N/r along the radius. The meaning of the different curves in the panels are given in their respective legends. The areas shaded in yellow and light yellow respectively indicate the regions (starting from r/R = 0) in which ∼95% of Φ(B) and Φ(N) are emitted.