During a phone call after 50 seconds my iphone starts to hear a buzz and the caller voice like a robot ( iphone 14 pro )

Greetings othman216,

If you hear a buzzing sound while making calls, the steps from the linked resource are the best place to start:

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." If you hear no sound or distorted sound from your iPhone, iPad, or iPod touch speaker

If the issue continues, contact Apple Support directly to Get Support. They will be in the best position to help.

We hope this helps!

Sincerely.