The sudrophone is a brass instrument invented by François Sudre (1844-1912) in Paris, its shape resembling that of an ophicleide. It was patented in 1892. It has a cylindrical bore and four Perinet valves. Its length is 86 cm and the bell diameter is 17 cm. The "valve" nearest the mouthpiece on the leadpipe controls a membrane to create a nasal effect, which François Sudre designed to make a sound like a cello or a violin. The instrument is very similar to the baritone horn and helicon. Acoustically these resembled the saxhorns, but the shape was different as the main tribe was doubled back on itself, giving a vertical appearance. Sudrophones included a device, based on a movable silk membrane, to modify the tone at the player's will.