How to make closed headphones out of open ones?

Question

Headphones

Good day!
Headphones with microphone Plantronics Gamecom GC307 are available, used in the office. The sound in them is quite pleasant, and you want to listen to music louder. But the headphones are open type, so if you make it louder, then the whole office listens to music with me.
The question is: is it possible to somehow upgrade them to reduce the level of external noise from them?

Answer 1

Wrap with cling film or cover with plasticine. Not at all. Buy normal ones. Open for that and open, so that the whole bus listened to the hits of Russian chanson with you.

Answer 2

Disassemble and carefully inspect inside the cup ...
You will immediately see what can be covered up, by the way, the Chinese often make an acoustic short circuit in headphones, using holes around the perimeter of the dynamic head holder, this is a sin, they also need to be covered up ...
But they sin not by chance , without these holes, the internal volume of the cup will immediately make itself felt, it must be filled with a chopped foam rubber sponge.