  We present a numerical investigation of shot noise suppression in mesoscopic
cavities and an intuitive semiclassical explanation of the behavior observed in
the presence of an orthogonal magnetic field. In particular, we conclude that
the decrease of shot noise for increasing magnetic field is the result of the
interplay between the diameter of classical cyclotron orbits and the width of
the apertures defining the cavity. Good agreement with published experimental
results is obtained, without the need of introducing fitting parameters.
