How do I prevent myself from sneezing loudly? Apparently my loud, embarrassing sneeze wakes up neighbors of my presence in the building.
This might take some training, as it is counter-intuitive, but it works like magic for me:
As soon as you feel the urge to sneeze building up, exhale completely. You might have to try a few times to find out how early in advance you have to start, and how fast or slowly you have to exhale. The idea is to have exhaled completely at the "point of no return", but also that you don't suffer.
In the end, if there is not much air inside you to burst out explosively, it will not make a significant noise. Good luck!
Personally, I hold in every sneeze. I can't say I recommend it, as this article points out: "The risk of a hearing loss injury due to holding a sneeze is low. However, it is not impossible."
Wiki's page on sneezing does a good job explaining what happens in a sneeze. Basically, nose hairs send a signal to the brain, which starts a massive response in the upper body's organs to expand and then contract the chest violently. Since this signal is sent through the nerves, there are lots of ways to try to stop the sneeze completely.
For example, some ideas from this wikiHow page are rubbing your nose, pinching the bridge of your nose, pinching the tip of your nose, pulling on your ear, etc. These suggestions come from the idea of sending another signal down the nerve and thereby sort of messing with your brain.
If you can't avoid the sneezing, then sneeze into the crook of your arm.
When wearing a long-sleeved, preferably soft and thick piece of clothing, this will muffle the sneeze to a good degree. This solution has the advantage that it's available in time for every sneeze. And in general, it is microbiologically much safer than sneezing into your hand – as in, potential germs will not spread with the next handshake, touching things etc..
While the sensation is building up, try to force the sneeze out, with all your willpower. It sounds weird but actually works.
Anytime I was on the verge of sneezing and tried to force it out and get it over with, the need to sneeze subsided. Using that actively requires a little bit more willpower, since you're trying to build up the intention to do something you actually don't want to while trying to avoid doing it involuntarily.
Make sure to blow your nose afterwards, the cause of irritation will probably still be somewhere in your sinuses.