An emergency vehicle siren is a loud sound device used by vehicles such as ambulances, fire trucks, and police cars to alert the public of their presence. The siren's distinctive sound helps clear traffic and ensures that other drivers yield the right of way, allowing emergency responders to reach their destinations quickly. These sirens typically produce a variety of tones and patterns, which can vary by region or vehicle type. The use of sirens is regulated by law, and their effectiveness is crucial in emergency situations, as they help save lives by reducing response times.