Parabolic acoustic mirrors called "whisper dishes" are used as participatory exhibits in science museums to demonstrate focusing of sound. Examples are located at Bristol's We The Curious, Ontario Science Centre, Baltimore's Maryland Science Center, Oklahoma City's Science Museum Oklahoma, San Francisco's Exploratorium, the Science Museum of Minnesota, the Museum of Science and Industry in Chicago, Pacific Science Center in Seattle, Jodrell Bank Observatory, St. Louis Science Center, Parkes Observatory in Australia and on the north campus lawn of North Carolina State University.