  We consider a two-particle interferometer, where voltage sources applied to
ohmic contacts inject electronic excitations into a pair of copropagating edge
channels. We analyze the impact of channel mixing due to inter-edge tunneling
on the current noise measured at the output of the interferometer. Due to this
mixing, the noise suppression typically expected for synchronized injecting
sources is incomplete, thereby reducing the visibility of the interference. We
investigate to which extent the impact of mixing on the noise visibility
depends on different shapes of the voltage drives. Furthermore, we compare a
simple model involving a single mixing point between the sources and the
quantum point contact to the more realistic case of a continuous distribution
of weak mixing points.
