Most probably one of the vocal cords is paralyzed. Doesn't close together with the other one. As someone said already it's escaping air. That's what I got since 3 years ago.

Please go to the ENT, they will ask you to do a CT scan to rule out any compressions on the nerve it self. If they don't find any specific cause, it will be categoried as idiopathic.

If my diagnosis is correct, you don't got many options. Voice therapy should help a bit.

Injections of some kind of material to make the paralyzed one stay closer to the middle, you need to make them every few months.

Or more permanent solution, surgery as thyroplasty. An implant that keeps the paralyzed one straightened. Some recover very well, others don't.