NO, Wotcha, will not be going to Bergen or Stavanger this trip - only time and funds to stay fairly close to Oslo. So that is why I specified in and near Oslo in the thread title. I was in the Irishman pub about 10 years ago but didnt find music on that occasion, I think there was a football match on. and my friend in Stavanger still lives there so hope to visit next trip (She will be away in Sweden when I'm in Oslo area).
In Bergen on the first of my 3 visits to Norway, must have been about 25 years ago, I attended a Norwegian night for tourists - a light meal and a presentation of dancing and music, mostly hardangerfele. I would think something like that would be presented in Oslo but I havent heard of it yet. I remember Soldier's Joy tune was presented as a "typical Norwegian reel" and I was thinking reels weren't typical of Norwegian music The woman next to me was from Orkney and she said "that's an Orcadian tune!", apparently as popular there as it is in Scotland, Ireland, America. The tune has the same title in Ireland and America but I dont know what they call it in Norway.

The problem I think with finding traditional music in Norway outside of the festival season is my asking "what's on?" and asking about "events". People are playing but not publicly. Betsy mentioned music in Voss (again not the area I will be in); I was at an event, a kappeleikin competition, but I learned that there was a local spelmanslag club where local traditional players met for lessons and group practice.

On my first trip I went as far as Lofoten, and I went there after having seen a photo in a Norwegian coffee table book of local Lofoten islanders playing standard 4-string fiddle. People I asked in Lofoten claimed there were no musicians in the area; they said the fiddlers had belonged to a single family which was no longer there - some men had died in fishing accidents.

But what about Oslo??? besides Scandi music, what about music from some of the immigrant communities in the city?