Hello lulub,
First, we want to get a better understanding of what's happening, along with isolating the issue a bit more.
To confirm, is this occurring with audio messages that you're sending, receiving, or both? We ask as this would help us determine whether this is a speaker or potential microphone issue.
We understand you've tested sending audio messages in other apps. Keep in mind that your iPhone has multiple microphones and speakers, so we'll need to test to see if the same microphone or speaker works in a different native app.
If this is occurring with audio messages you're sending, test out that microphone using the Voice Memos app with the steps in If the microphones on your iPhone aren't working.
- "Open the Voice Memos app.
- Tap the Record button
, speak at the bottom of your phone, then stop the recording. - When you play back the memo, you should hear your voice clearly."
We look forward to hearing back from you.
Regards.