A pushbutton switch for use in a keyboard incorporated in an electronic typewriter, work processor, or the like gives a tactile feel to the finger of the operator corresponding to a clicking operation and, at the same time, produces a clicking sound. The switch comprises a casing, a switching device...http://www.google.ca/patents/US4642433?utm_source=gb-gplus-sharePatent US4642433 - Pushbutton switch with aural confirmation of operation
