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United Airlines passengers to see targeted ads on seat-back screens
(www.cbsnews.com)
This is a most excellent place for technology news and articles.
As others have said, "in-ear monitors." However, it's not technically about the quality. Earphones sit in the outer ear, while IEMs go at least a little bit into the ear canal. They do better with blocking out sound, which is better for audio quality, but sometimes you want to be able to hear things around you, so it's a matter of context.
Also, while audiophiles can get wild with it (and there's a lot of snake oil in that area), I just got some Salnotes Zeros for <$20 and they're great.