Gorillas have a belch vocalization, which is sort of like, 'I'm OK, you're OK.' They do a pig grunt, which is reprimanding. They sing, they laugh, and they hoot, which grows into a chest-beating display.

Quote

“Gorillas have a belch vocalization, which is sort of like, 'I'm OK, you're OK.' They do a pig grunt, which is reprimanding. They sing, they laugh, and they hoot, which grows into a chest-beating display.”