Harp-like, plucked string instrument native to the alien planet Gurnil, from the 1968 science fiction novel The Still, Small Voice of Trumpets by Lloyd Biggle, Jr. It's a smaller version of the torril. It uses an inflected pentatonic scale.
Expanded from "Still, Small Voice," originally published in April 1961 in Analog.
Biggle actually has PhD in musicology.
Suddenly he noticed the instrument standing on a low table near her cot. It was similar to the one he'd seen in the portrait, but only two feet high and looking more like a child's toy than the medium for great art. Its wood frame was unadorned but richly polished.
"It's so small!" Forzon exclaimed. "The one in the portrait was enormous!"
Her finger at her lips reminded him that he had raised his voice. "That's a torril," she said softly. "A man's instrument. An instrument for public performance. The frame is elaborately carved and built precisely to the musician's height. When the young torril player is growing up he must have a new instrument yearly. This one is a torru, a woman's instrument. Its tone is well-suited to the boudoir but is much too delicate for concert use."
"A marvelous, whispering tone," Forzon said. He got to his feet and bent over the torru. The slender strings were of some tightly twisted fiber, white and—every fifth string—black. He plucked them gently, one at a time. “It's an inflected pentatonic scale!” he exclaimed. "Primitive, and at the same time highly sophisticated. Curious."