A stacked-ring, slow-wave acoustic telemetry isolation system and method for use with tubular assemblies such as drillpipe or production tubing comprising an acoustic wave transmitter, the acoustic isolator behaving such that a “down” wave propagated toward the isolator is reflected back substantially in phase with an “up” wave propagated from the acoustic wave source away from the isolator. The acoustic isolator is similarly effective in reflecting “up” propagating waves originating from below the isolator, hence further protecting the acoustic wave source from possible deleterious interference. It causes substantially all of the emitted wave energy to travel in a chosen direction along the drill pipe, thus aiding the efficiency of acoustic telemetry said pipe.