Reave enemy pop effect?

I am not sure you are allowed to post links to outside places on here but I just respected my duelist to a Vaal Reave build. I love the build but after looking at several other players I was curious what the effect is they when an enemy dies to Reave they almost make like a glass pop sound.

It is like in this video.

https://www.youtube.com/watch?v=YPHntjOy65k

Is this an effect you pay for or is this based on some kind of item or what?

Thank you to anyone who answers.

This is the shatter sound from killing frozen enemies. If you crit with enough cold dmg you will freeze the enemy.
Combine this with Herald of Ice and you will explode packs.

Fantastic!

Thank you very much!