How do I pronounce these Katakana Onomatopoeia (words that sound like noises)?

Question

こんばんは。

When I have been reading Manga recently I have encountered many onomatopoeia words such as シャカシャカ as in 'Brush Brush' and パタパタ　for 'rush rush/flap flap' but I have found some words such as　シャッ for a 'zoosh/swoosh' sound but what is the 小さいつ (small tsu) ッ suppose to mean in this onomatopoeia when it is at the end of the word? for another onomatopoeia word, シャッ I read it as 'Sha'? but does the ッ change the way I pronounce the word in any way? Other examples of onomatopoeia words include しゃーっ 'shuum' and ボコッ 'thump'.

Sorry if the onomatopoeia words are wrongly translated. I just basically want to know what is the small 'tsu' (Hiragana or Katakana) do to the word when it is placed at the end because from my knowledge it usually indicates a pause for words like 学校【がっこう】.

ありがとうございます。

Answer 1

When っ or its katakana counterpart ッ appears word-finally, it's commonly a glottal stop //ʔ// or an implosive, "unreleased" stop at some other point of articulation, for me usually implosive //k//.

Glottal stops appear in English too, most common example being "uh-oh".

First English word I can think of which has an implosive stop is "yep".

EDIT:
Update as I was not fully understanding the question.

っ(ッ) at the end of an onomatopoeia usually works to intensify it.
Many onomatopoeia denoting crushing, slashing, cracking, i.e "destructive" ones tend to have ッ at the end.

ドカッ sounds stronger than ドカ (hitting something), バキッ stronger than バキ (breaking something), and so on.

"Soft" onomatopoeiae tend not have っ(ッ) at the end.
Examples include サラサラ(river water quietly streaming), パラパラ (flipping through pages of a book)