I seem to recall that most if not all of these digital aids have an e2e transmission protocol between each aid running at something like 2.4.
The Marvels use Bluetooth at 2.4 GIGAHertz. The Signia/Rexton (originally Siemens) system uses 3.4 MEGAHertz2, or nearly 1000 times lower in frequency. That is where the improved ear to ear transmission reliability comes from. That said goes direct from the phone to each ear because it can connect to two devices at the same time. The e2e is used for microphone directionality and Cros/BiCros purposes.
You’re ignoring this member’s posts.