Instead, most opera houses use the sound reinforcement system for subtle boosting of offstage voices, onstage dialogue, and sound effects (e.g., church bells in Tosca or thunder in Wagnerian operas). Acoustic Enhancement systems are most often employed in traditional opera houses to improve the sound of the orchestra, and have little if any effect on the sound of the voices. In a review of the State Opera of South Australia's performance of Wagners' Ring cycle at the Adelaide Festival Center Theatre, Michael Kennedy of The Sunday Telegraph, London, wrote: “The balance between the orchestra and the voices has been ideal.”