I have it. My tics are mostly inaudible. My wife actually refused to believe me for some time that I even had it. Eventually she started noticing things and accepted that I wasn't messing with her.
My tics began developing around age 5 or 6 and I was diagnosed shortly after by a neurologist with a "mild form" of Tourette's syndrome. When I was a young child my tics were very noticeable and obvious. Over the years I learned ways to hide them and internalize them as best as I could. Some of them became unnoticeable to those around me, some remained obvious, and some could be noticed to someone watching closely. They ranged from noises, to movement of limbs, fingers, shoulders, etc. I've never had a verbal tic, (as in a specific word or language based tic).
Coworkers, friends, etc. are typically unaware I have Tourette's Syndrome unless I disclose it. Then they can sometimes pick my tics out here and there.
When I was a kid, the tics usually changed with the seasons for some reason, and some came and went as I aged. The first one I can recall, a grunting noise, is the only one that has remained consistent from the beginning. It is the first one I learned to hide and no one has heard me make the noise since I was around 7 or 8 years old. I can satisfy that tic with a little click of my tongue on the roof of my mouth. Someone could hear it if they were close enough, but I doubt anyone ever has aside from maybe my wife.
I don't know how it is for others, but stress is a major hurdle for me. Stress causes my tics to worsen in intensity, and my need to suppress them causes a lot of strain, which again, makes them worse. When it gets very bad, it is like a tornado inside of my head. I cannot focus or puts my thoughts in order. I have a coping mechanism that works for me to basically 'reset', but it's kind of difficult to even realize what the problem is when in that state.
If anyone has any questions, I'm happy to share.