A stethoscope for auscultating sounds from a subject, the stethoscope including a housing, a curvilinear convex diaphragm supported on the housing for interfacing with the site being auscultated and for receiving sounds therefrom, an enclosed acoustic chamber supporting on the housing and communicating...http://www.google.ca/patents/US4903794?utm_source=gb-gplus-sharePatent US4903794 - Acoustical amplifying stethoscope
