Why won't my random death sound script work, what else am I doing wrong?

function addSound()

    local sounds = script:GetChildren()
    local chosenSound = sounds[math.random(1, #sounds)]
    local soundCln = chosenSound:Clone()
    soundCln.Parent = script.Parent.Head
    soundCln.Name = "DeathSound"
    soundCln:Play()

end

if script.Parent.Humanoid.Health == 0 then 
    addSound()
end

No errors, nothing. The solution is probably just in my face but I'm not too good with scripting yet. Help would be appreciated.