Voices looks like robots....

[arkrog]

Hi every one.
I downloaded VLC on my new macbook pro, and when i'm playing videos on VLC, the voices looks like robot.. But not all the time.
I thought it was the computer, but I tried several other options (like youtube, or spotify, etc...) and the sound is just great, so it's not a problem from computer.
And this is weird, because I said, sometimes the voices are normal, then for no reason, it's like a robot voice..

Is it happening to other people too or just me ? What can I do to fix this issue ?

Many thanks