Perfect Soundproof Room

I am a composer extremely sensitive to sound. To create my works, I spent millions of dollars building an absolutely soundproof, completely sealed recording studio in my home. This room has no windows, its walls are 50 centimeters thick, and when the door is closed, you cannot even hear the sound of a passing tank. One night, I was focused on composing inside. At three o'clock in the morning, I put down my pen to rest, and accidentally glanced at the analog clock on the wall (the kind that has a second hand). After staring at the clock face for a few seconds, I suddenly ran madly toward the door, frantically scratched the heavy soundproof door with my nails, let out desperate wails, and eventually died of exhaustion. What happened?