Use these characters in a conversation and you will sound 100% more local.
In this lesson we look at 10 exclamative particles in Mandarin Chinese, (Wiki)
These are the noises people make to show surprise, laughter, or pain etc. Examples in English would be things like;
hahaha, oi, huh, um, what! etc.
Different regions will use some more than others, but here are some common ones used in Taiwan. Listen to people around you and see which ones they use. After a while, these sounds will become natural to you, and you will say them without thinking as your Chinese level improves.