Florencia Rastelli was mortified. As an expert barista, she had never spilled a single cup of coffee, she said. But last Monday, as she wiped the counter at Chiave di Bacco, the cafe where she works, she knocked over a glass and it shattered loudly on the floor. The customers all stood still, petrified, Ms. Rastelli recalled. “I was like: Of all days, this one,” she said. “Even a police officer popped in and asked me to keep it down. I was so embarrassed.”

The people of Cremona are unusually sensitive to noise right now. The police have cordoned off streets in the usually bustling city center and traffic has been diverted. During a recent news conference, the city’s mayor, Gianluca Galimberti, implored Cremona’s citizens to avoid any sudden and unnecessary sounds.