IF a single note from a trumpet (say) is played, it will cause first, say, a compression, then a rarefaction, and so on. IF a speaker were reproducing that sound, in phase, it would first move forward, and then back. Out of phase, it would first move back, then forward.

Given the phase anomalies that exist in most real world environments, and the fact theat most PM is highly complex, abs phase has not been shown to be audible at all. Richard Greiner did do some studies that showed that i9n some very simple tiones, with a very clean environment, it si audible. However, that does not extend to real world listening of real world PM.
-akhilesh

When two tones are generated, their phase relationship with one another matters because of their interaction with one another. If they are out of phase, they will cancel each other out and the sound will drop off. If phase moves in and out of destructive and constructive interference, then there can be rhythmic throbbing of cancellation and reinforcement. But if the movement in phase is such that no destructive interference results, then phase is imperceptible. The bottom line is that if you can hear something as a result of phase changes, then what is heard is cancellations that cause frequency anomalies - not the phase.

-akhilesh

• Look for Absolute Phase on this page