Hey there ddoenges,
Thanks for reaching out to the Apple Support Communities.
To get started, does your Beltone hearing aid have a built in microphone? If so, does the microphone work without issue when using other calling or video apps? If so, and if you try and record a voice memo using the steps in the following link with your hearing device connected, are you able to hear yourself without issues: Make a recording in Voice Memos on iPhone - Apple Support
Make a basic recording
1. To begin recording, tap .
2. To adjust the recording level, move the microphone closer to or farther from what you’re recording.
3. Tap to finish recording.
If not able to hear yourself in the Voice Memo, you may need to reach out to Beltone support to look closer into your hearing device. You can reach out to Beltone's support directly from this link here: Support - Beltone
If you are able to hear yourself in the voice memo recording without issues, or if your hearing device doesn't have a built in microphone, have you tried restarting your iPhone since noticing the issue? If not, then while this may seem like a simple step, it can sometimes help with resolving some unexpected issues like this.
For help with restarting your iPhone, check out this link here: Restart your iPhone - Apple Support
How to restart your iPhone X, 11, 12, 13, or later
1. Press and hold either volume button and the side button until the power-off slider appears.
2. Drag the slider, then wait 30 seconds for your device to turn off. If your device is frozen or unresponsive, force restart your device.
3. To turn your device back on, press and hold the side button (on the right side of your iPhone) until you see the Apple logo.
Keep us updated on what you find.
Take care.