More correctly termed absolute polarity, absolute phase describes a situation in which the phase remains constant throughout a signal path compared to a reference. In real situations, absolute phase means that the + and – polarity of a system are maintained from beginning to end. For example, the leading edge of a sound wave usually causes a positive voltage in a microphone, and this voltage remains positive through all the connections and components in the audio system until it reaches the loudspeaker, where it produces a positive (forward) motion in the speaker diaphragm. Some audio engineers or sound live engineers states that absolute phase is essential for the best sound quality.