How to make the sound currently playing fade out once stepped on a block?

How to make the sound currently playing fade out once stepped on a block?

So I've made a script that looks like this

local SoundID; local Volume;

local SoundID = 0 ; local Volume = 1;

local function CreateSound(soundID, volume, parent) local sound = Instance.new("Sound", parent); sound.Volume = 0; sound.Name = "_PlayOnTouchedSound"; sound.SoundId = "rbxassetid://".. soundID; sound.Looped = true;

sound:Play()

repeat
    sound.Volume = sound.Volume + .1;
    wait(.1);
until
    sound.Volume >= volume;

end;

script.Parent.Touched:connect(function(other) if other and game.Players:GetPlayerFromCharacter(other.Parent) then local player = game.Players:GetPlayerFromCharacter(other.Parent); local PlayerGui = player.PlayerGui

    if not PlayerGui:FindFirstChild("_PlayOnTouchedSound") then
        CreateSound(SoundID, Volume, player.PlayerGui);
    elseif PlayerGui:FindFirstChild("_PlayOnTouchedSound") and
        PlayerGui:FindFirstChild("_PlayOnTouchedSound").SoundId ~= "rbxassetid://"..SoundID then
        PlayerGui:FindFirstChild("_PlayOnTouchedSound"):Remove()

        CreateSound(SoundID, Volume, player.PlayerGui);
    end;
end;

end);

How can I make that once stepped on a special block, the sound starts to fade out and it takes at least 3 seconds for the sound to completely stop?