You can apply envelopes to individual events. Envelopes, known as ASRs (attack sustain, and release) give you the ability to control an event's fade-in, fade-out, and overall level.
When you create an event, handles are added that are used to set the envelope. As you drag these handles, a volume envelope appears.
Choose Edit > Mode > Event (or click the Event Mode button 
in an editor's playbar) to enable event-editing mode.
Hover over the top of an audio event.
When you see the envelope cursor (
), drag the volume line to the desired level. As you drag the envelope, the event’s gain is displayed in dB.
Hover over the upper-left or upper-right corner of an audio event until the fade offset cursor is displayed 
.
The fade handle is displayed in yellow when no fade is present:
. . . and is displayed in green when the fade is too small to be displayed:
Click the corner of the event and drag to create a fade.
To remove a fade, drag the end of the fade curve back to the edge of the event.
Right-click the fade-in or fade-out area to display a shortcut menu.
Choose Fade Type from the shortcut menu and choose a fade curve from the submenu:
If you want to change the default fade type that is used when fading an event in or out, choose Options > Event Default Fade In or Default Fade Out and choose a fade curve from the submenu.
The fade curve you choose will be used for new fades (existing fades are unaffected).