The Description of the Vulcan Lyrette from the original Star Fleet Technical Manual reads that this is "An unusually harmonious and melodic accompaniment or solo instrument, whose origin is lost in Vulcan antiquity. It combines the tonal qualities of a harp, lute, sitar, and to some extent, violin."
They are usually made of Li'Pon and Sher Skah woods, with a Bahun'ahb inlay. The lowest pitch it can reach is 60 cps, and the highest is an astounding 3180 cps. The only instance of one of these being played in the actual films, was in "Star Trek: The Final Frontier." Spock was seen sitting by a campfire with Kirk and McCoy on shoreleave playing "Row, Row, Row your boat" on his Vulcan Lyrette.