Aum to bring calm:
Aum/Om: The Sound of the Universe, and the connection of the true self.
Calm: Quiet, tranquil, serene, peaceful, still.
There is no doubt that there's a connection between the word calm and the word Aum/Om.
Both have a positive effect on our physical & mental states when we say them.
Whenever we are struggling to get our brain in gear. We tend to use the sound, om or mmm, or aauu or some other iteration of the sound. In fact we tend to use a similar sound when we breathe out, when we are in pain, when we are trying to soothe, or get someone else to relax.
These two word are similar to each other because not only do they have the same sound, but they have the same outcomes.