iPhone Hearing Aids Rating
The iPhone works great for Hearing Aids.
The iPhone XS Max has two HAC Ratings for Hearing Aids: M3 and T4. In fact, Apple has had the two ratings since the iPhone 5s.
Industry Standard Rating
The ratings are are the American National Standard Institute hearing aid compatibility standards. They measure the radio-frequency interference and how well the inductive coupling works.
The ratings are based on a scale from 1 to 4.
The iPhone XS Max is hearing-aid compatible under the FCC requirement guidelines since they are within the acceptable range for radio-frequency and inductive coupling.
While this is good news, it doesn't mean that your hearing aid may work. It's highly recommended to test the iPhone at an Apple store. Simply ask one of the workers to test your hearing aid with a phone. (Floor models don't have the cellular activated, you will need to use a special phone for testing.)
Enable Telecoil ModeTo activate Hearing Aid mode on the iPhone XS Max, go to Settings > General > Accessibility. Hearing Aid mode on the iPhone XS Max modifies the phone's acoustic settings to improve compatibility with hearing aids set in "T" or telecoil mode. Telecoil mode is not enabled by default on the iPhone XS Max. Check your hearing aid manufacturer as you may have better options than telecoil mode such as Bluetooth.
Oticon Opn 3
The Oticon Opn 3 works great with the iPhone XS Max. The sound quality is great and very clear. Audio is stream directly into your hearing aids without anyone knowing via the MFi connection bridge.
The MFi connection bridge is like a Bluetooth connection but doesn't work the same way. You can't just sync the hearing aid to any Bluetooth device.
One thing to keep in mind whether your using Airpods or Made for iPhone hearing aids, people can still hear the sound if you have it too loud. Just because the device is in your ear doesn't mean that the sound doesn't escaoe if it's loud enough.