Mic not recognised when trying to use Google Voice in Google Docs in windows 10

[niikk]

I'm wanting to use Google Voice to transcribe audio. I've set up the file inside Google Docs and clicked on the microphone icon - it goes red - but no sound is getting through to the program. Looking inside my settings via the speaker icon, all my settings are fine. And it works fine with Cortana. However looking at Microphone inside Settings, the Google app is not included among those you can choose to use with your microphone. And there is no offer of adding apps to the list. Does anyone know a way around this? Google Voice is a terrific, highly intuitive speech recognition service and I'd planned to use it a lot.