AirPod Pro sound

Sounds like something is blocking the microphone in the black grill. With a soft tooth brush gently go along it but don’t poke into it. They are sensitive and picking up movement causing feedback. If issue still persists try this

1. Put your AirPods in their charging case, and keep the lid open. 
2. Press and hold the setup button on the back of the case for about 15 seconds, until the status light on the front of the case flashes amber, then white.*

it will reset the AirPods then try reconnecting them to your iPhone if issue still persists I would setup appointment via your iPhone to see Genius at the store