Absolute phase

http://en.wikipedia.org/wiki/Absolute_phase

High fidelity

In the realm of high fidelity reproduction of music, absolute phase refers the phase of the reproduced sound waves relative to the original sound waves, or to the relative phase of the various channels of stereo or multi-channel reproduction. In most cases, it is actually a question of the polarity of the channels, i.e., an equal phase shift of 180° at all frequencies. Some audiophiles claim[1] that reversing the polarities of all the channels simultaneously makes a perceptible difference in the sound quality, even though the relative phases of all the channels are preserved.

某些發燒友認為即使將喇叭同時極性相反過來，本來的相對相位未變，仍然可聽出不同....