Effects of phase manipulation on speech intelligibility through communication headsets.

A masking level difference (MLD) paradigm was established by rewiring the earphones of a communications headset out-of-phase. Essentially no release from masking could be measured, however, on a crew of listeners in the cabin of light aircraft. The experiment was replicated in the laboratory so that the exact phase of the aircraft noise masker could be controlled. The substantial MLD obtained in this environment led to the conclusion that the noise reaching the ear in the cockpit was of random phase, which almost eliminates the MLD. Therefore, rewiring headsets out-of-phase provides no advantage in intelligibility.