  The velocity field in the lower solar atmosphere undergoes strong
interactions with magnetic fields. Many authors have pointed out that power is
reduced by a factor between two and three within magnetic regions, depending on
frequency, depth, the radius and the magnetic strength of the flux tube. Many
mechanisms have been proposed to explain the observations. In this work, SDO
dopplergrams and magnetograms of 12 bipolar active regions ($\beta$ARs) at a 45
second cadence, are used to investigate the relation between velocity
fluctuations and magnetic fields. We show that there is an asymmetry within
$\beta$ARs, with the velocity oscillation amplitude being more suppressed in
the leading polarities compared to the trailing polarities. Also, the strongest
magnetic fields do not completely suppress the five-minute oscillation
amplitude, neither in the spot innermost umbrae.
