117 hours:

I've spent about 15 hours so far listening to news stories. One nice thing about news stories is that the domain is somewhat restricted, so new words get repeated a lot.

Examples of words which have recently become very familiar are words for "report", "news", and "company". Many geographical and political terms have become very familiar. Sadly, words dealing with war and loss of life are also becoming very familiar.

Examples of words which have recently become somewhat familiar are words for "government", "president", "prime minister", "science", and "environment".

Words for "crude oil", "atomic", and "fuel" have appeared, but they have not yet become familiar.

Listening to the news is a lot like narrow listening. The domain of discussion is restricted, subjects change slowly from day to day, and the subjects are interesting. An entire news broadcast is longer than the 1-3 minutes recommended for narrow listening, but broadcasts can be edited in Audacity, and individual stories are usually 1-3 minutes, give or take.