What does "crossfade" refer to in audio editing?

Crossfade in audio editing refers to a technique where the volume of one audio source gradually decreases while the volume of another audio source gradually increases. This gradual transition creates a seamless blend between the two audio tracks, as opposed to an abrupt switch. By employing crossfades, audio engineers can create a smoother listening experience, making transitions between songs, sound effects, or voiceovers more pleasant and professional.

This method is particularly useful in music production, radio broadcasting, and any situation where a consistent auditory experience is desired, helping to maintain flow and avoid sudden jarring changes in audio levels. The other options do not capture the essence of a crossfade, as they suggest either an abrupt change or unrelated concepts like unifying tracks, which does not specifically apply to the gradual blending characteristic of a crossfade.