Before the Nokia Amber update, Nokia Lumia 920 was recording (albeit in very high quality) mono audio.
But, post Amber update and with Nokia Pro Cam, you can now record in stereo. According to the datasheet, there are not simply two but three high amplitude audio capture microphones. Until now only one has been active for recording video (and secondary for noise cancelling?)
Here’s a comparison as shared very nicely with us by HrabiaMol (thanks!). I suggest putting on some headphones/play through stereo speakers that are of some decent distance for channel separation.
Having Stereo Audio helps give a little bit more depth to the video (scene permitting). I believe all the 92x will get stereo recording post amber/nokia pro cam.
Nice. Nokia giving users hardware now, and then when MS gets their act together, the software to utilise it.