Whatâs common between the worldâs biggest alarm clock and the worldâs loudest alarm clock (featured above) is that they can wake even the soundest of sleepers. The former uses vibrations to wake you up, while the latter with ear-shattering noise. In a way, you wouldnât want either of them in your bedroom. Hear for yourself how loud the worldâs loudest alarm clock (video) is, after the jump.