iphone 7s microphone static

I tried the recommendation to test the microphone hardware using Voice Memo, that is actually where I noticed the problem. So from the start, I don't think software fixes /advice may be applicable. Willing to try. I tried my camera apps they all record a mostly constant, hissing static. A decibel meter app shows 67 dB which is pretty loud. a conversation is 55dB so this would be loud voice on the verge of shouting. it's registering as a real sound, even in a silent room. I have read the Lightning port can be the culprit and replacing the charger port may solve the issue? my Apple repair tech guy will probably advise "I can get you into a iphone 13 or 14 pretty decent price why do you want to keep this 7 going?" Because it's the last one with a home button