How much does it cost to get microphone fixed on iPhone 7 ?
How much does it cost to have the top microphone fixed at the Apple store?
iPhone 7 Plus, iOS 11.4.1
It does not say specifically but look here for Other Damage
iPhone Service Pricing - Apple Support
You might try searching for repair in your area for other sources
E.g.
https://www.re-tech.com/iphone-7-microphone-repair/
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I have no commercial any applications I may mention in a post. My comments are based solely on my own use.