Shalaft's Syndrome was an extremely rare human illness that caused hypersensitivity to sound. Genetically, all the male members of a family inherited it. Jean-Luc Picard had the condition, but was treated for it. Shinzon also had the condition, although it took many years before he was properly diagnosed and treated.
In 2379, Beverly Crusher used Shinzon's possession of the syndrome as a factor in determining that the Praetor of the Romulan Star Empire was indeed a clone of Picard. (TNG movie & novelization: Nemesis, TNG novel: Resistance)
