  Recent results of Singh et al. (2016) show that the emergence of an active
region (AR) can be seen in a strengthening of the f-mode power up to two days
prior of the region's formation. In the original work, ring diagram analysis
was used to estimate the power evolution. In this study, we make use of the
Fourier-Hankel method, essentially testing the aforementioned results with an
independent method. The data is acquired from SDO/HMI, studying the ARs 11158,
11072, 11105, 11130, 11242 and 11768. Investigating the total power as a
function of time, we find a similar behavior to the original work, which is an
enhancement of f-mode power about one to three days prior to AR emergence.
Analysis of the absorption coefficient $\alpha$, yielded by a Fourier-Hankel
analysis, shows neither absorption ($\alpha > 0$) nor emission ($\alpha < 0$)
of power during the enhancement. Finding no changes of the absorption
coefficient (i.e. $\alpha = 0$) is an important result, as it narrows down the
possible physical interpretation of the original f-mode power enhancement,
showing that no directional dependence (in the sense of inward and outward
moving waves) is present.
