The erhu is a two-stringed bowed musical instrument, often called the 'Southern Fiddle' or 'Chinese violin.' It has a long neck and a small hexagonal or octagonal sound box covered with python skin. Unlike a Western violin, the bow hair is permanently threaded between the two strings, meaning the player cannot remove the bow from the instrument easily. The strings are tuned to a fifth (usually D and A). There is no fingerboard; the player produces different pitches by pressing their fingers against the strings in the air. The erhu is known for its incredibly expressive, melancholy tone, which closely resembles the sound of a human crying or singing. It is a staple of Chinese opera and traditional orchestras, but in recent years, it has been used in modern fusion and film scores to provide an evocative, haunting texture.