What is it?

Suddenly, there was a loud thud at the door. The onomatopoeia in this sentence is _____________________.

The sausages are sizzling in the pan. The onomatopoeia in this sentence is _____________________.

The loud boom of the fireworks scared the dog.  The onomatopoeia in this sentence is _____________________.

We clapped our hands in time with the music. The onomatopoeia in this sentence is _____________________.

The snake hissed at me as I got closer. The onomatopoeia in this sentence is _____________________.

The magician waved his wand and poof, a rabbit appeared. The onomatopoeia in this sentence is _____________________.