When I'm not on my own and I'm in a situation that is making me cry, I always stop myself from making ANY sound, to the point that people in the room or even my partner sitting next to me don't notice it. Tears stream down my face and I'm just suppressing and fighting that lump in my throat, as if my life depends on it. Sometimes when I'm close to dissociation I can have blank expression, just stating at nothing while tears come down. 

I wonder if it has to do with years and years of practicing to contain myself and my emotions in my front of my parents because I've been known for being a  sensitive 'cry baby' as a kid. So I just stopped showing any real emotions as I grew up.