I have recently tried to transcribe more songs by ear and it goes alright as long as I know the tuning. I was wondering if there is any tips or techniques for determining what (open) tuning is used in a song? One trick I have already used is looking up videos or finding a good cover on youtube. But what can one do when there is no video? For example how would one determine the tuning on this song (Erin go bragh by Dick Gaughan)or for example this one (Lakes of Champlain by Martin Simpson) if one only had the audio to go by?
Thank you very much in advanced for any help!