The new AirPods Pro sound like (har har) the first in a line of game-changing AR devices to me. If you can take external sounds and manipulate them in way that removes the "noise" (har again) and emphasize what you personally find interesting, well, that's a whole new reality. No, it's a whole new approach to reality.
You could already use the old version of AirPods (AirPods Plain?) as a part-time, special-case hearing aid and emphasize sounds you wanted to hear as if your ears where in another location. This is similar, but so much more inventive. Take the sounds you want to hear, remove the ones you don't. That's step one, and it sounds like what Transparency Mode claims to do.
The next step -- and you've got the start of this with always-on Siri -- is when your devices start adding sounds to the filtered "noises from reality". Maybe your AirPods listen for sounds your own ears can't hear like your baby whimpering. Maybe they're connected to a baby monitor and, if the sounds are as small but as important as your baby turning over onto their stomach, it unmistakably alerts you.
Think about how neat it would be to have a subaural Siri, where your AirPods can hear what you're not quite vocalizing and change how your hearing works in the world. I had a taste of that dictating a message into my Apple watch once, where in a loud situation I was able to Siri my way to a message without anyone hearing me.
And that's just Siri taking input. That's child's play in the world of audio AR. Now imagine that's a means of interacting with "superhuman" hearing -- hearing what happens in another place or hearing sounds that were subaural or simply interacting with notifications as they happen. That's powerful. That's a new interface for computing that can fundamentally change the way we live.
Does that make sense? Step one is take out the noises we don't want. It's filtering. Step two is to insert noises over what's left that make our hearing more useful. That's Augmented Reality. Augmented Reality (AR) is what's important to our future -- not Virtual Reality that's a complete escape, but Augmented Reality, the addition and layering onto (or off of) what we already experience.
And that's interesting and exciting.