Once again we affirm that whether a sound is funny, mundane, or scary depends entirely on what’s making it.

• 02.033 groaned Dori
• 06.035 groaned Bilbo,
• 06.085 but Dori groaned ‘my poor legs,
• 07.012 The dwarves groaned
• 07.099 the branches groaned, the forest moaned,
• 07.148 groaned the hobbit.
• 10.010 through the shallow water to lie groaning on the shore.
• 10.010 Groans came from inside,
• 10.012 so after a few more groans he got up
• 10.039 There were no more groans or grumbles.
• 11.032 The dwarves groaned,
• 13.003 they groaned.

Goblin poetry: can’t help but laugh and shake in your shoes!

• 04.020 Hammer and tongs! Knocker and gongs!

The OED uses frogs and ravens as the only exemplars of beings which make this sound in the first definition of “croak the noun” and “croak, the verb”.  Intrigued, I read onward.  Obsolete second meaning includes “forbode evil (like the raven)”, without note or explanation about this anthropomorphization, just one example to make the hair rise:

1609   Shakespeare Troilus & Cressida v. ii. 193   Would I could meete that roague Diomed I would croke like a Rauen, I would bode, I would bode.

Goblins’ singing is so laughable as to be called croaking, but crow and bird croaks are eerie – and perhaps the sounds of Roäc are truly ominous!

• 04.018 The goblins began to sing, or croak,
• 04.036 croaking, jibbering and jabbering;
• 11.008 and again the harsh croak of a bird.
• 11.011 followed ever by croaking crows above them,
• 15.014 he croaked
• 15.022 croaked Roäc,

“croak, v.” OED Online. Oxford University Press, March 2015. Web. 27 May 2015.

In the first case, the dwarves are making a racket which is amusing to us readers and in the second case the crackling fire is dangerous.

• 02.039 and crackling and creaking
• 06.084 in crackling fire.