Simple Explanation

The change in timing between two signals, or the delay in the timing of a signal over a period of time.

Concise Technical Definition

Phase shift refers to the phase change of a signal relative to another, or its shift in time. Phase delay is a specific type of phase shift that is constant for all frequencies of interest, where a sine wave is displaced in time from the original waveform. This concept is often used interchangeably with group delay, though in some systems, phase delay and group delay may not be the same.

Layman-Friendly Analogy

It’s like watching a video where the audio and visual are slightly out of sync—one is delayed by a constant amount, causing the sound to lag behind the picture.

Industry Usage Summary

Phase shift and phase delay are important in signal processing and audio systems to describe the time-based changes in signal timing. In systems where phase characteristics exhibit ripple across frequencies, phase delay and phase shift can affect the sound, causing distortion or undesired effects. Phase delay is often used to describe how systems introduce delays across all frequencies, while phase shift may vary more dynamically with frequency.

Engineering Shortcut

The time-based shift in phase of a signal, typically with a constant delay across frequencies (phase delay).

Full Technical Explanation

Phase shift refers to the change in the phase of a signal over time, specifically the relative timing of one signal in relation to another. Phase delay is a specific instance of phase shift, where the sine wave is displaced in time from the input signal by a constant delay across all frequencies of interest. Phase delay is typically associated with the group's delay, but there are instances where they may not be identical, especially in systems that exhibit ripple in phase vs. frequency characteristics. This phenomenon can impact the performance of audio systems by altering the relationship between different frequencies, which can introduce distortion or impact the clarity of sound, especially if the phase shift is not uniform across the frequency spectrum.