Modulus of the reflection coefficient at the lower boundary of the g-mode cavity (upper panel) and damping rate in the g-mode cavity at the frequency ν_max(lower panel) as a function of frequency of maximum oscillation power for the sample of red giants of Mosser et al. (2017). The same quantities are shown for the upper boundary of the p-mode cavity in transparent blue. The colors of the solid symbols correspond to the lower pie chart in Fig. 9 (i.e., to the detectability of the multiplet signature). Errors correspond to the uncertainties in the observed radial mode linewidth (see main text).