Something that is very loud, any sound that is voluminous, i.e. has lots of volume. We measure sound using units known as decibels. A decibel is one-tenth of a bel, which represents a logarithm of a ratio. For instance, a jet engine is about 120 decibels. It is therefore decibelic.
Dude, this concert is so decibelic, I think I'm gonna have to go outside before I go deaf!