Hello Ayaelias,
Based on what you've told us, it sounds like you're able to send audio messages but the recipient isn't able to hear what you're saying. For basic information, you can learn how to listen to audio messages here: Send recorded audio messages on iPhone - Apple Support
To troubleshoot the issue, we recommend sending an audio message to someone else. If they're able to hear you without issue, we recommend that the first recipient follow the steps here: If you hear no sound or distorted sound from your iPhone, iPad, or iPod touch speaker - Apple Support
They may find these steps helpful:
1. Remove all screen protectors, films, or cases from your device.
2. Check the speaker opening to see if it's blocked or dirty. On iPhone only, make sure that the receiver isn't blocked or dirty.
3. If necessary, clean the speaker or receiver opening with a small, soft-bristled brush. Make sure that the brush is clean and dry.
4. Go to Settings > Sounds (or Settings > Sounds & Haptics), and drag the Ringer and Alerts slider back and forth a few times. If you don't hear any sound, or if your speaker button on the Ringer and Alerts slider is dimmed, your speaker might need service.
5. If you hear sound, try making a call with your iPhone and turn on speakerphone. On iPad or iPod touch, make a FaceTime call. If you still can't hear, or hear static or crackling, then your network or reception could be the issue. Try to call again later, or from a different location.
Thanks.