Non-native speakers often think the long a in jag sounds like an o, but native Swedes don't agree. There may be some variation in pronunciation, but mainly this is because we have more vowel sounds than most other European languages, so learners need to train their ears to hear the sounds correctly.
Thank you for that info. But still, I do not think it is like the English "a:" or short "a" sound. Doesn't this recording sound a bit off to you? In the previous example https://www.duolingo.com/comment/5522714 it is completely different. Are you able to show me some source with model pronunciation, if you know one? Thanks! :)
The new voice sounds OK. The one on top here sounds OK too: http://sv.forvo.com/search-sv/jag/
but there is variation in how people say the word and there are some cases where it's more understandable that people hear it as an o.
PS I listened to the sentence in your link and I agree it sounds different, but I think both are good. I think of both as a sounds but my idea of that is a Swedish a, it's difficult to transcribe our sounds into English.
In some languages (Finnish, Swedish, German ...) , the keyboard may have a double dot " ¨ " on the upper right end (same row as qwerty).
You could also try to change the keyboard / windows language setting to "Swedish", which you can do in windows on the taskbar, with the language toolbar. With my UK laptop I switch daily between the different language toolbars. You would have a shortcut for that on the taskbar, no trouble there.
Once the language is switched, you will find öäå / ÖÄÅ on the right end of the rows qwerty / asdf. Then it takes some training to get it right, but it is doable :-)