[Stonedpossum]

Gah! Ok, I have,

local frame= CreateFrame("Frame")
frame:RegisterEvent("PLAYER_AURAS_CHANGED")
frame:SetScript("OnEvent", function(frame)
    local t = 0
    frame:SetScript("OnUpdate", function(_, elapsed)
        t = t + elapsed
        if t >= 1 then
            frame:SetScript("OnUpdate", nil) 
            if IsMounted() then
                PlayMusic("Interface\\AddOns\\OnTheRoad\\music.mp3")
            else  
                StopMusic()
            end
        end
end)

But it still doesn't even work.