An external, self-contained laryngeal prosthesis is adapted for use by a tracheostomized patient having a surgically-formed "pseudoglottis" separating the trachea and the hypopharynx. The prosthesis includes a housing and a fitting for attaching the housing to the tracheostoma formed in the patient's...http://www.google.com/patents/US4494252?utm_source=gb-gplus-sharePatent US4494252 - Laryngeal prosthesis
