Heave ho! is the sort of thing one chants when hauling on the lines of a sailing ship in order to keep time with other sailors.  As a kind of work song, I’ve tagged it as low.  Beorn’s use of it in Chapter 7 is not the same, but we’ll keep it here as an interjection and non-lexical vocable.

• 04.020 Ho, ho! my lad!
• 04.020 Ho, ho! my lad!
• 04.022 and to the ugly laughter of their ho, ho! my lad!
• 04.022 and to the ugly laughter of their ho, ho! my lad!
• 07.042 O ho,
• 09.049 Heave ho! Splash plump!

No citation.  I grew up in a region where learning 18th century nautical history and jargon and drinking songs were just part of the local picture.