Correlation of the g-mode model spectrum with the power spectrum of a simulated time series of round-trip travel time. Top panel: for l = 1 only (similar to Fig. 1 in FS18). The black line is for the result after optimisation while the green it is before optimisation; middle panel: for l = 2 only. The black line is for the result after optimisation while the green it is before optimisation; bottom panel: for l = 1 and l = 2 (similar to Fig. 2 in FS18). Left panel: for the median value of the sum of the correlations at lag=0 and lag=ν₁ obtained over the 2000+ simulations. Right panel: for the maximum value of the sum of the correlations at lag=0 and lag=ν₁ obtained over the 2000+ simulations.