A police siren is a loud, attention-grabbing sound used by law enforcement vehicles, such as police cars, to alert the public of their presence. The siren helps clear the way for emergency response, signaling that the vehicle is responding to a call or pursuing a suspect. Typically, police sirens produce a variety of tones and patterns, which can vary by region or department. These sounds are designed to be heard over traffic noise and other environmental sounds, ensuring that pedestrians and drivers can react appropriately to the approaching emergency vehicle.