Sound effect description: Dozens of people have rhythmic stepping sounds Timeline: 0-10 seconds features: -0-3 seconds: Slowly and orderly militarized steps (65BPM) -3-7 seconds: Gradually accelerate (90-120BPM), increase volume -7-10 seconds: Rapid suppression (150BPM), increased echo -10 seconds: Suddenly stop Sound quality: -The sound of trampling on dry sandy land -Mixing leather shoes and military boots -Low frequency enhancement creates a sense of threat -Slight metal friction suggests a chain lock Emotions: inevitable fate, collective pressure, tension and fear