MacBook Pro 2017 15" Internal Microphone Picks Up Physical Tapping but Not Speech. Somehow It Works for Siri.

My internal microphone on my MacBook Pro 2017 15" doesn't work properly. For the most part it doesn't pick up any sound except when I physically tap on the MacBook, even when in system preferences where the internal microphone input registers zero bars when I talk but plenty when I touch the laptop. I have played with the input volume and put it all the way up. No one can hear me in Zoom or Discord calls. However when I ask Siri something it works perfectly.

I have rebooted, reset the NVRAM or PRAM, and updated to the latest macOS.

Plenty of others have suggested testing in safe mode to see if the problem persists there. When I did, the computer did not register any sound inputs. The internal mic was nowhere to be found. What does this mean?

After exiting safe mode I had the same problems as before.

I scanned my laptop with the free version of Avast and it came up with zero issues.

In an old post, someone said that the mic is disabled in safe mode because it's nonessential, meaning that you can't even test the sound input using safe mode. Is this true?

I was planning on reinstalling MacOS to see if it would resolve the issue, but since I can't find my backup disk drive, I have no place to back up my files just in case the reinstall goes wrong. I'll keep looking for the drive another day.

Basically, are there any other solutions that I can try before I can find my external disk drive?

Thanks in advance for any advice you can offer.