  The noise-enhanced trapping is a surprising phenomenon that has already been
studied in chaotic scattering problems where the noise affects the physical
variables but not the parameters of the system. Following this research, in
this work we provide strong numerical evidence to show that an additional
mechanism that enhances the trapping arises when the noise influences the
energy of the system. For this purpose, we have included a source of Gaussian
white noise in the H\'enon-Heiles system, which is a paradigmatic example of
open Hamiltonian system. For a particular value of the noise intensity, some
trajectories decrease their energy due to the stochastic fluctuations. This
drop in energy allows the particles to spend very long transients in the
scattering region, increasing their average escape times. This result, together
with the previously studied mechanisms, points out the generality of the
noise-enhanced trapping in chaotic scattering problems.
