Hi folks,
Had my second Lumia 930 about a week now (first one was 3 days old when it bricked itself) and I've noticed a very similar issue..
I've been testing speakerphone and Skype with my wife and she can't hear anything coming from my end, so it appears as if there's no audio for this part.
If I test the mic by recording some video, then I do get audio, but it's very quiet.
I've tried adding a voice note in OneNote, and it doesn't appear to be working at all there either. All I get is a bit of static.
Cortana, however, doesn't seem to be having any issues. It's tested fine, and it looks like it hears (and understands) me when I just speak normally.
I believe I already have the Denim update, although if someone wants to tell me the version number I'll be happy to confirm this. I've tried soft and hard resetting the phone, and I've reset it via the Lumia Recovery Tool too. Nothing seems to have had any impact on this issue.
The next step for me I think (unless someone can recommend something else) is to send the phone back to the carrier for repair/replacement, which I hate doing
ETA: Just done a little more testing on this...
If I run the MS camera, then I don't get any audio at all except maybe some static. I can't hear my voice at all. However Lumia Camera behaves slightly differently. Using the Lumia Camera with its default settings, it is able to pick up audio but not much. I can hear my voice but it's very quiet. BUT if I change Lumia Camera's video settings to record with Dolby 5.1 Surround Sound, then I get much better quality audio.
I'm still confused though, and I have no idea what this means in terms of figuring out whether this is hardware or software related.