[2][3] In audio, a change in polarity refers to an equal phase shift of 180° at all frequencies, usually produced on one channel by reversing the connections of two wires.
[5] The ear is sensitive to the periodicity of a waveform at low frequencies; tests have shown that absolute phase can sometimes be heard by test subjects listening with monaural conditions (a single loudspeaker, or headphones sending the same signal to both ears.)
Audio engineer Douglas Self concludes "there is a prima facie case for the audibility of absolute phase", especially for high impulse sounds such as percussion.
[6] When dealing with power electronics, the phase of the voltage and current at various points in the system relative to one another are important.
To solve this problem, the phase of the signals relative to absolute time (UTC) is measured using instruments relying on GPS.