I rewrote this.
Well... I skipped iOS 17, but on iOS 16, there was no true hearing aid function, just the Live Listening, which required me to place my iPhone close to the sound source I wanted to listen to.
The amplification I get from iOS 18's hearing aid mode is vastly superior to what I got from Live Listening on iOS 16. More clear, more stable. Volume, I don't know. It's not the volume itself that matters, more whether the sounds are sharp and distinct, not muddled.
I'm sorry but you are wrong on that. Transparency Mode and the ability to add your audiogram to AirPods was introduced on the AirPods Pro in IOS 14 way back in 2020. AirPod Pro 2s were launched in September 2022 around the same time that IOS 16 was released.
An article I found but there are many out there:
Apple has introduced hearing aid functionality to Airpods Pro as part of their new IOS update, don't throw your hearing aids away just yet though
www.hearingaidknow.com
My main point about volume is purely aimed at people with worse than Moderate hearing problems. It goes without saying that the sounds have be sharp and distinct but that's what the different frequency boosts from the audiogram to each ear do.
Someone with severe or profound hearing loss will need much more volume going into their ears to hear much at all.
I've heard two conflicting opinions on the volume of them using 18.1. A few saying they can go louder and others say the opposite.
Here is a better explanation of what I said. I was working at the same time and I wasn't clear.
It is whether IOS 18.1 provides more volume than
the previous option or less. I've heard people are saying both which can't be possible.
As I've said before they work very well for me running IOS 17.7.1 and I think I have better control as they’ve really simplified the menus in IOS 18.1.
Anybody living in a country that has not been approved can get them working as hearing aids as long as they use an IOS older than 18.1. I've only been told that it's not possible to roll back to IOS 17 but it's not something I have tried as I never updated to 18.1 in the first place.