Which instrument is a trapezoidal Chinese hammered dulcimer?

The Yangqin is indeed the trapezoidal Chinese hammered dulcimer. It is a string instrument that consists of a set of strings stretched over a wooden frame, which is typically trapezoidal in shape. Players use mallets to strike the strings, creating a distinct sound that is integral to traditional Chinese music.

The design of the Yangqin allows for a broad range of tonal possibilities, making it versatile for both solo performances and accompaniment in ensembles. Its history dates back to the 17th century, originally influenced by the Persian santur, and it has become a staple in Chinese folk and contemporary music styles.

In contrast, the other instruments listed serve different functions and possess unique characteristics. The Pipa is a plucked string instrument similar to a lute, the Erhu is a two-stringed bowed instrument, and the Dizi is a bamboo flute. Each of these instruments plays a vital role in the richness of Chinese music but does not share the dulcimer's trapezoidal shape or hammered playing technique.