Wu Collection, Lower Volume Radical: Stone (shí) Pí Kangxi strokes: 18 Page 837, Entry 37 According to the Sound Rhymes (Jiyun), it is pronounced pí. It is the same as the character for a thunderclap. Zhang Heng in his Rhapsody on the Western Capital (Xijing fu) wrote: The sound of thunderclaps and echoes resonate and increase in volume.