Problem with mic during phone calls and with Siri

I have a Verizon iPhone 6 Plus with version 9.0.2 installed. It seems that this update may have caused microphone issues during phone calls and while using Siri. The microphone was working correctly before this update. I do have an otterbox case over it and have since I first got the phone in July. I removed the otterbox case and noticed no difference. I've checked the microphone for debris and there's no debris, I've turned the phone on and off several times, and I've had to pretty much yell into the phone for people to hear me (even then, it's still quiet). I've called different people with different phones and carriers, and the results were the same--they could barely hear me. I recorded a short video and the microphone picked my voice up well and I heard it clearly. So I'm wondering if this is more of a software problem than a hardware problem. I haven't tried restoring the phone to an earlier firmware, and that's something I'd save as a last resort, as well as resetting the phone.

Is this a known problem with the recent firmware update? Is there a fix for this?