How do autonomous vehicles detect emergency vehicles prior to “seeing” them?

Question

As a human, we can hear the siren of an emergency vehicle approaching and take action (pull over, do not proceed into intersection etc) well before the emergency vehicle gets to us. How do autonomous vehicles such as those from Waymo/Cruise do this? Do they only take action when they “see” the blinking lights? Could a tow truck or other maintenance vehicle with orange blinking lights fool a autonomous vehicle into thinking it was an emergency vehicle?

In: 10

Answer 1

Many jurisdictions have sensors on traffic lights that detect traffic priority/traffic preemption signals emitted from the front of emergency vehicles. Basically a specially coded IR light pulse. Autonomous vehicles could have the same sensors installed, forcing them to pull over and stop for emergency vehicles.