Just for all others, what Domi and me are talking about.
Inside of violins and many other bowed instruments, there is a small stick inside, a sound post, often described as the soul of the instrument.
(btw. you shouldn't cut out this edge of your own violin at home, it actually doesn't make it sound better, I swear )
This small stick has a very very strong influence on the sound quality of the instrument, only its perfect position gives the best sound. It is not glued, it just sticks between the 2 decks and it can fall out of its position if the instrument is handled roughly.
If you want to know more about this topic, it is described more detailed here: