I thought it was common knowledge that it makes you feel like you could speak a foreign language better. I don't think it's that obvious that the improvement would be objective or that others around you would feel the same way about you.
(And of course there's a Ballmer peak in any case.)
Amusingly, the study found the exact opposite!
https://journals.sagepub.com/doi/10.1177/0269881117735687