So, you would have to do something like this:
local fade_start = 3 --//Time from ending to start fading away
while wait(.1) do
if Sound.TimeLength = Sound.TimeLength - fade_start then
--//Fade away with slowly lowering the volume.
end
end
Untested and written on mobile. When I get the chance I will revise and test it, but hopefully you got the basic idea.