[UnderProtest]

The only reason this even looks like a problem is that humans don't follow the law.

In most jurisdictions if there's an emergency vehicle running flashers and/or siren behind you on the same side of the road you're supposed to slow, pull over, stop, then proceed only when the vehicle passes you.

If the emergency vehicle parks behind you then you have effectively been pulled over.

Pulling over safely is practically the first thing a self-driving car team works on. It is very easy to detect flashers and sirens. So... no problem.

Well, except that self-driving vehicles may accidentally be pulled over by firetrucks.

[dsnuh]

So if the autonomous vehicle hears the sirens, does it start to pull over, or wait until it can also detect flashers? What about a loud stereo playing a siren sound or a car with flashers installed on it? I'm just wondering, because although I know this sounds like a pretty simple problem, I don't think that it is.

[UnderProtest]

Again, the law and custom already cover this.

When you hear a siren you're to become alert for the possibility of flashers behind you. You are not supposed to just start pulling over because it may not be on the same road as you and pulling over may block traffic. Imagine if every car in a crowded downtown pulled over every time the drivers could hear a siren. Instant gridlock.

So a siren played loudly on the radio will not cause a rule-following car to pull over, regardless of who or what is driving it. I presume you're talking about siren sounds in music, but...

Installing flashers that produce the same pattern as official police flashers and/or playing a continual siren is impersonating an officer. That's a serious crime.

Fake flashers will probably cause self-driving cars to pull over but they'll also cause humans to pull over. Not a self-driving car problem.

In the future police flashers can have a cryptographic element emdedded in the flash pattern that a self-driving car or a human-driven car with sensors can authenticate but that's an enhancement over the current situation.

It's one of the best-defined situations in traffic because it's precisely the fallback behavior. Detect emergency vehicle behind you, pull over as far as is safe, wait. If a self-driving car can't do that then it's hardly self-driving at all.

The real trouble, which you haven't brought up, is when the traffic is already at a standstill and an emergency vehicle approaches. The soft and gradual scooch-scooch movements that we have to do to clear enough space for the emergency vehicle are a much tougher case.

You can pull over a self-driving car. You just may have difficulty getting past it to an emergency.