A rock tumbler apparatus having a dual barrel assembly with energy-absorbing air gaps is provided. The air gaps may be evacuated or back-filled or filled with a sound absorbing gas or other material. The rock tumbler may be operably attached to a programming system, which may include a sound dampening cover. The rock tumbler may be programmed, for example, to tumble during certain times of day, continually, to pause at various time intervals, and to tumble in one direction or another.