I'm setting the playback speed for a sound, why can't I hear a difference?

I've made a pickup script and I wanted to add a sound effect that varies in pitch, I've setup the script so the sound's PlaybackSpeed is randomized, then print the PlaybackSpeed afterwards so I can ensure it's working. The issue is, while the printed text shows that the PlaybackSpeed was indeed randomized you cannot hear a difference at all.

Here is the script, it's in a normal script

math.randomseed(tick())
local crate = script.Parent
local invCrate = game.ReplicatedStorage["Light Crate"]
local sound = script.Parent.Pop -- Pickup sound

script.Parent.ClickDetector.MouseClick:connect(function(player)
	print(player, " picked up ", script.Parent)
	-- Sound stuff is here
	sound.PlaybackSpeed = math.random() + 0.1
	print(sound.PlaybackSpeed)
	-- This is just for picking up the crate
	local newPart = invCrate:Clone()
	newPart.Parent = player.Backpack
	crate:Destroy()
end)

and the sound part has PlayOnRemove set so it'll play when the crate is picked up