Crossfades are used to create smooth transitions from the end of one audio segment to the beginning of another. They do so by creating a fade out and a fade in over the transition region. Waveforms to crossfade between should be positioned in different tracks (or can be in the same track, in a back-to-back manner), adjacent if possible.
To crossfade, make a selection with your mouse and include in it the beginning and ending sections of any waveforms you wish to include in the crossfade. The highlight should extend a bit beyond the end of the waveform(s) to fade from, and should start a bit before the beginning of the waveform(s) to fade to. Or, if Edit > Snapping > Snap to Blocks is enabled, the highlight will easily adjust itself to the beginnings and endings of the waveforms. (You can also adjust the highlight by holding the Shift key down when doing a left-click near the edge of the selection.)
After establishing a highlighted area, you need to select the waveforms to include in the crossfade by holding down the Ctrl key and left-clicking on the desired wave blocks. Next, choose Edit > Crossfade (or Crossfade from the right-click menu) and the type of crossfade you want to do to crossfade between the selected waveforms.
Three major types of crossfades are available. Choose Linear for an even grade, and Sinusoidal for a curved, sine-like slope to the fade. Logarithmic will fade the amplitude of a signal at a constant rate, producing a steeper slope at one end of the fade, depending on whether you are fading in or out. (Both Logarithmic In and Logarithmic Out options are at your disposal.)
The Crossfade toolbar button uses Linear fades by default. Choose the Crossfade command from the Edit menu or right-click menu to specify a different crossfade type.
The fade curves created with Crossfade can be modified by enabling the Show Volume Envelopes and Enable Envelope Editing options in the View menu.
