Mantras are sometimes also applied to change circumstances, to regain a healthy condition for example. Those mantras are specially formulated to carry a certain vibrational power. For such purposes it is important that the proper pronunciation is also imparted. They probably have heard of OM too. What might be new is that all these words have, in fact, the same meaning and also the same origins.
Physicists know that all of matter, our whole Universe, is made of vibrational energy.
Atoms are no longer pictured as solid balls orbiting a solid center or proton. Electrons and protons are now explained as energy concentrations with a certain vibrational pattern. This is the vibration which is called by readers of the Bible Amen or the word of God. Moslems call it Amin. Since OM is the original vibration, all other mantras are derived from this one Master Mantra.