Audm was an article narration service which was eventually acquired by the New York Times. The service is now part of the NYT but still narrates articles across many publications — including the New Yorker.
Accessibility. Not everyone has 20/20 vision.
Yeah AFAIK they have no relation to each other, other than the occasional friendly acknowledgement that the other exists. Perhaps that is enough?
So that people can listen to the article, I would assume.
That explain why an audio version exists, but not why the audio is hosted by a different, unaffiliated publication.