The low frequency fluctuations of the flux at the ports of a wave guide structure connected to electron reservoirs or black body sources are investigated. At equilibrium the cross-correlation of the flux fluctuations are negative independent of whether the flux is subject to Fermi or Bose statistics. In the presence of transport the cross-correlations for a Fermi system remain negative whereas for a Bose system at certain ports the correlation function can become positive. We emphasize that waves emanating from different mutually incoherent electron reservoirs or black body radiators can nevertheless give rise to interference phenomena in the cross-correlation function. Specific examples are discussed which illustrate the appearance of phase sensitive cross-correlations generated by waves emanating from mutually incoherent reservoirs. © 1991.