As seen in MacRumors, iOS 18 beta testers can set a new Siri wake word using Vocal Shortcuts, a new accessibility feature. Go to Settings > Accessibility > Vocal Shortcuts > Set Up Vocal Shortcuts, then find and tap “Siri” to try it.

It won’t work with HomePods. And your iPhone won’t acknowledge it unless you pause after saying the word. That’s good; otherwise, you learn just how frequently you say a word like “computer.”