Your instrument may need adjustments from time to time. There is a wooden dowel inside your instrument that is force-fitted between the top and bottom of the instrument, near the right foot of the bridge. This is the
sound post, and its placement affects the strength and quality of your instrument's sound and the balance between strings. If the instrument is seriously jarred, the sound post can be moved out of alignment. Also, as the seasons change and your instrument expands and contracts, your sound post may need to be realigned. Do not attempt to make these adjustments yourself. Take your instrument to a violin shop, and work with a trained technician to make this adjustment. You will need to try out your instrument after the adjustment, and often it takes several tries to get the balance between strings, the resonance, and the brightness of the sound just the way you want it. You should be able to accomplish this in a single visit to the shop.
If the soundpost ever becomes completely dislodged and rattles around inside your instrument, immediately loosen your strings and take the instrument to a luthier to have the soundpost reseated. If you do not loosen the strings, the tension of the strings may push the unspupported bridge through the top of your instrument and result in a nasty and expensive repair.