Technical & Engineering
Phase Shift
A technical acoustic anomaly resulting in a detrimental change in the phase of a broadcast signal or audio waveform.
What is Phase Shift?
Phase Shift occurs when the timing relationship between two audio channels becomes misaligned. In stereo broadcasting, the left and right channels must remain phase-coherent for the soundstage to render correctly; when they drift out of phase, the resulting cancellation at the combined mono signal can produce audible thinning, hollowness, or near-total loss of specific frequency bands.
Phase problems are especially damaging on FM broadcasts because a large fraction of listeners — notably in cars with imperfect stereo separation — effectively hear the mono sum of the stereo signal. A commercial that was produced with out-of-phase elements in the stereo mix may be virtually inaudible to those listeners. Station engineering chains therefore include phase-correlation monitoring and in many cases active phase-correction processing before final transmission.
Why it matters
When stereo channels are out of phase, severe audio cancellation occurs, severely degrading the listener's experience and making commercials inaudible.
Related terms
- Actuality (Sound Bite)— Unfiltered, raw audio recordings captured on location outside the controlled studio, featuring interviews or ambient background sound.
- A-D Converter— Analog-to-Digital Converter; specialized hardware that translates continuous analog electrical signals into binary digital data (1s and 0s).
- Ad-Lib— Unscripted, entirely improvised vocal delivery by a professional broadcaster, host, or voiceover talent.
- AES / EBU (AES3)— A professional digital audio transfer standard developed jointly by the Audio Engineering Society and the European Broadcasting Union.