Adjective : the reverberant booms of cannon.    From Dictionary.com. 

Once more he called out into the unreverberant silence, but already he was certain that he would never know the answer.    From Wordnik.com.  [The Lost Worlds of 2001]

Every footstep, every word, vanished instantly into the unreverberant void; after they had gone little more than half a kilo - metre, Lt Calvert could stand it no longer.    From Wordnik.com.  [Rendezvous with Rama]

Cliff looked around the now familiar, comforting little cabin, and then thought of the lonely emptiness between the stars-the unreverberant abyss through which a man could fall until the end of time.    From Wordnik.com.  [The Wind from The Sun]

The unreverberant Profound.    From Wordnik.com.  [0 1172. From "The Inverted Torch" by Edith Matilda Thomas. Stedman, Edmund Clarence, ed. 1900. An American Anthology, 1787-1900] Reference