There are basically three ways vibration data acts in an acoustic instrument. 1.) It is absorbed / damped / killed within the instrument. 2.) It is maintained as it continues to travel within the instrument. 3.) It is externally damped by the air (i.e., becomes sound).
If the instrument encourages #3 too much, it will sound loud, crisp, and dry. If too much #2, the instrument may reverb or feedback if mic’ed, and will sound wet, glossy, and inarticulate (but smooth). If too much #1, it will be quiet and dead.
Where it really gets interesting, though, is that it’s not just about balancing 1, 2, and 3–it’s about **how** 1, 2, and 3 are balanced throughout the entire frequency range. For instance, an instrument where no vibrations become #1 will sound unfocused and awful because the instrument would be letting all frequencies dominate at once, instead of tastefully carving away unwanted frequencies so a King David can emerge from the marble. Past this, if certain frequencies remain #2 while others become #3, you can get any variety of complex evolutions of sound from initial attack to final decay.