A cushion for a headset earphone comprises a resilient ring having opposite input and output faces, and a through-opening defining an interior surface between the two faces. An electrosurgical apparatus of the invention includes an active electrode assembly having an active electrode screen surrounded by a plurality of flow protectors. The trans-conductance circuit is configured to amplify a periodic signal produced by a crystal. In response to selection of a filter category, a visual depiction of the selected filter category is displayed in the view.