This tinkle comes when Bilbo stumbles over a golden thing, therefore I give it a “low” tag, but the tinkle of broken glass upon the entry of a foe could have a very different register.

• 13.018 and a tinkle

“Thump” is another word whose register depends on what is causing the thumping.  Dwarves threaten to thump plates in Chapter 1 and trolls thump about in a slapstick fight scene in Chapter 2.  While the mood is eerie in Chapter 8, the thumping of feet or of dwarves to the ground are clumsy and low in comparison to the menacing, listening place.  In Chapter 9, Bilbo’s heart thumps during the daring rescue – but their danger is  not particularly great.

• 01.067 Pound them up with a thumping pole;
• 02.070 and thumping,
• 08.001 and the quiet was so deep that their feet seemed to thump along
• 08.105 thump to the ground
• 09.029 Bilbo’s heart thumped every time

“Thud” seems to be an onomatopoeic word the register of which depends on exactly what is doing the thudding.  The feet of oliphaunts on their way to war?  Dangerous and high.  Barrels full of dwarves?  Low.

• 09.050 thudding on top of ones below,

Bilbo’s stammer in Chapter 18 points out the distance between his station and Thranduil’s.

• 18.046 said Bilbo stammering

A squeal is another sound made by prey animals and vulnerable persona when in danger.  Definitely “low”.

• 05.056 Give me time!’ But all that came out with a sudden squeal was:

Things which squeak are obviously either funny or contemptible.  Another “low” tag for an onomatopoeia word.

• 01.063 while the hobbit ran after them almost squeaking with fright:
• 01.110 squeaked Bilbo
• 02.050 oo are you?” it squeaked,
• 05.087 How it squeaked!
• 05.111 when we twisted that nassty young squeaker.
• 12.073 in a frightened squeak,
• 13.010 he squeaked aloud.
• 13.023 He squeaked
• 13.028 or he would not go on squeaking.’
• 16.033 squeaked Bilbo.
• 17.013 squeaked Bilbo,

The Chapter 16 instance of “splutter” occurs when Bilbo stumbles and falls into a stream on his super-silent mission to reach Bard without the dwarves’ knowledge.  Definitely a funny bit of slapstick.  Johnson (of “Boswell’s Life of___” fame) called this a low word, and I’ll happily take that evidence.

• 05.041 and spluttered.
• 05.073 and spluttered
• 08.109 so now they all began to splutter
• 08.123 and spluttered
• 09.055 He came up again spluttering
• 16.017 shivering and spluttering,

“splutter, n.” OED Online. Oxford University Press, March 2015. Web. 20 May 2015.