I think it's more that language is unpredictable, illogical. It changes every few years. You can identify generations by their slang but it varies place to place for no reason at all.

[The signs will be there: a few pauses where he just 'forgets' Ricki altogether, which always coincide with an abrupt change of topic when he can hear again. He doesn't do much asking after sentences he's missed.]

What was going on in your world when you left?