Despite casperdacrook encountering a moment where Arthur Morgan hums a tune only after playing through the game multiple times, Reddit user DrCarabou claimed that this singing happens all the time in their playthrough.

Source: https://gamerant.com/red-dead-redemption-2-arthur-morgan-sings-thanksgiving-gift-video-clip/

New adventures in sound keep coming; pure-voiced solos; beatboxing that hums and clicks and raspberries and waterfalls; unexpected chorale laments.

Source: https://www.theguardian.com/stage/2023/nov/05/the-week-in-theatre-king-lear-lyonesse-pied-piper-review-kenneth-branagh-kristin-scott-thomas-lily-james

Rings and hums come and go, so when a new hum with no obvious source appeared, I thought nothing of it.

Source: https://www.pressandjournal.co.uk/fp/opinion/columnists/6084103/honey-bee-inspire-technology-ben-dolphin-opinion/

Then, there is metacognition, a buzzword that hums throughout the book and entails “experiencing your emotions consciously” and “refusing to be controlled by them.”

Source: https://www.newyorker.com/magazine/2023/10/23/build-the-life-you-want-the-art-and-science-of-getting-happier-oprah-winfrey-and-arthur-c-brooks-book-review