Ursula K Le Guin's "The Silence of the Asonu" aka "The Wisdom of the Asonu" (short story, free): Some glimpses of human nature
Story summary.Asonu of title are both a world & aliens who live there. They have a curious trait: after the age of 6 or 7, they stop speaking; an adult would perhaps utter a dozen monosyllables in as many years; yet they are able to live perfectly normal lives in their community. These are pastoral nomads, going wherever their "flocks of anamanu" take them.
Humans find this lack of speech very interesting, & often interpret it as something deeply spritual. Here we learn of the methods men employ to try figuring out the aliens' "wisdom" & what they've learnt.
Fact sheet.First published: 1998. (Where? Links all over the web mention Orion, but that's a publisher. I would have assumed it was in some collection of author published by Orion, but author's ISFDB page doesn't list any collection published in 1998.)
Download full text from Lightspeed.
Related: Stories of Ursula K Le Guin.