Is dun dun dun an example of an onomatopoeia?

Eye of the tiger by Survivor

That's the theme song to Troll 2. Amazing how these syllable-codes will sometimes evoke the memory of an actual melody. I think you have in mind a section of a piano piece by Chopin, believe it or...

every song

a Dun is a certain colour of a horse. Dun horses have golden/yellow-like bodies with a black main, tail, and legs. beautiful horses :)

Here are the notes to play it: B B B G A A A F#