The twang is pronounced as a very subtle and even crackling sound. It is similar to the sound produced when twirling a tuft of hair in the ear. It is characterized by a short, fragmented, intermittent, equal and uniform size sound. The following are the causes and pathogenesis of the twanging sound. Pathogenesis: The pathogenic bacteria of gas gangrene grow and multiply mainly in the wound and rarely invade the circulation to cause sepsis. Gas-producing bacteria produce alpha toxin, collagenase, hyaluronidase, lyso-fibrinase and deoxyribonuclease, etc. The destruction of red blood cells causes hemolysis, hemoglobinuria, oliguria, kidney tissue necrosis, edema, liquefaction, and muscle necrosis, causing rapid spread and deterioration of lesions. The decomposition of sugar produces a large amount of gas, which makes the tissue swell; the decomposition of protein and the liquefaction of gelatin produce hydrogen sulfide, which makes the wound stink. Due to local ischemia, plasma exudation, and the action of various toxins, the tissues and muscles in the wound, further necrosis and decay, more conducive to the reproduction of bacteria, making the lesion more deteriorated. Large amounts of tissue necrosis and exotoxin absorption can cause severe toxemia. Certain toxins can directly invade the heart, liver and kidneys, causing focal necrosis and hypofunction of these organs.