Voice Memo Microphone not working

Thanks but everything that the front-facing camera and sensor assembly is responsible for is working 100%. The only problem I can find is the bottom microphone does not work with the Voice Memos app. What is frustrating is that the bottom microphone DOES work with voice calls. When you are using your iPhone like a regular phone and holding it to your ear the microphone in use is the bottom one right? Or is Voice Memos the ONLY app that will ever use that bottom Mic?

@larry767 Bottom microphone is the one used for normal phone calls. Hard to tell what's causing your issue without some testing.

OK this is what I thought. I tested the phone call scenario by phone my work phone and leaving my self a voice mail. I switch back and forth between speaker phone and normal phone during the message and when I play it back, there are no audio issues. Both mics picked up my voice clearly.

The Voice Memos app definitely does not pick up my voice at all. The only thing that registers and caused any kind of blip in the scrolling wave form is if I physically tap on the phone in the region where the mic is. It is difficult to tell on playback if it is playing an audio recording of the noise or if it just an electrical blip caused by something else.

Either way, I find it EXTREMELY odd that the mic clearly works for one piece os software and not for another - both of which are part of the base iOS and not a third party. Is there different hardware portions employed between the two tasks that would be the culprit? I did also connect a pair of Apple earbuds with the inline microphone with the same result.

@larry767 Good you found some good will to do some thorough testing as this adds some valuable info. Microphones work both fine, so we can rule them out. Lower microphone has a fair number of rails connecting it to the logic board. Hard to tell what each data line does exactly in detail, I'm no engineer and there's no guide explaining what they do precisely outside Apple engineering boundaries. Once sound reaches connector, it goes to the audio IC mostly through resistors and I'd think either one of them has gone bad or the audio IC itself. Depending on time available one may try check continuity and/or replace the the audio IC in a monkey see monkey do fashion, but yet this is a microsoldering job. I'm afraid there isn't anything else you could do to try fixing the issue on your own.

I had forgotten that this phone has had microsolder repairs. I bought the phone in dead condition. No charging current, would not turn on, even with a battery swap. I used a mail in repair service and do not get a detailed report of what they all fixed. I generally just receive the phone back, go through a checklist of things to test including the mics and satisfy myself that it works. I did not notice the non working mic until recently so have not gone back to the repair shop to ask their thoughts (it's a $20 Canada Post trip for it each way). However, after reading your thoughts - it is possible the Voice Memo's code could be more finicky (or use other paths within the schamatic) than the code used to send audio from the mic to the cell network. I do also notice that the phone tends to get warmer than normal on the back under the rear camera (in the area of possibly the audio IC) under some conditions. Always a risk when you microsolder that one thing will lead to another. Thanks.