Quote Originally Posted by Mark Trail View Post
In every comic book I've ever read where the hero can tell someone's blood pressure they doing it via super-hearing (see, eg. Daredevil).

No reason not to assume Homelander wasn't listening to Stan's Korotkoff sounds
You can't tell blood pressure from hearing. You can tell how fast a heartbeat is, but blood needs to be stopped in an artery and then allowed to flow to know blood pressure. The numbers started as the millimeters of Mercury that would hit when the blood started flowing again in a particular instrument. It is an arbitrary number that has been standardized. There is nothing to hear.