English: Early microphone used at radio station CKUA, University of Alberta, Edmonton, Canada, the first educational broadcasting station in North America and a Canadian cultural icon, on display in Canada's National Music Centre museum. The microphone is a Western Electric Model 357 double-button carbon microphone, developed around 1921, which was extremely widely used in the 1920s for broadcasting because of its low distortion. It is often called the "ring and spring" microphone because the small cylindrical pickup unit was suspended at the center of a metal ring using springs to isolate it acoustically from its supports.