The mud wah evolved from an earthen musical instrument, and is named after the sound "woo woo wah" blown out. The modified mud wow is in the shape of a bull's head, with two horns running across the top and hollow. There are three kinds of large, medium and small, respectively, high, medium and low, the total range of f-f2, including all semitones.

The improved mud wah sound is simple and bright. Among them, the alto Niu Tau mud wah, which can be played solo, is 15 cm wide and 12 cm long, with a blow hole in the middle of the upper end and seven sound holes (one on the left of the first six).

When playing, use the tiger's mouth with both hands, the right finger presses the right three-tone hole, and the left finger presses the left four-tone hole. Often plays pentatonic pieces in the key of F, bB or C. The whole set of bull head-shaped mud wow has been used for music stage performances.