Audio: crossfade (0:06)
crossfade plays two rhythms and crossfades between them. The crossfade figure shows the waveforms of both rhythms and illustrates the effect that crossfading has on amplitude.
Crossfading is an envelope technique for transitioning between two sounds. It creates the auditory illusion by fading out one sound at the same time as fading in another.
In crossfade both rhythms are contained within their own ASR envelope. The actual crossfade occurs during the period when the two sounds overlap. This is when the release segment of the first rhythm overlaps with the attack segment of the second rhythm. The first rhythm reduces in amplitude whilst the second rhythm increases.
The shape of a fade is either a line or a curve. A line can only ever have one shape, it must be straight. A curve can take many shapes
Here are two of the most common shapes for a crossfade:
A linear crossfade is used in crossfade to emphasise the fact that the two rhythms are different.
Crossfading has practical uses. It helps a disc jockey (DJ) to transition between two recordings. It is used when sampling a loop to ease the transition from the end of the loop to the beginning by removing artefacts, clicks and pops, caused by a rapid transition between two significantly different amplitude levels. Writing a mashup, a mixture of two or more songs, is one of the creative uses of crossfading.