It’s simple. With closed headphones, the housing is designed in such a way that little or no ambient noise can be heard. In addition, hardly any noise from the headphones reaches the outside. Because of this, care is taken in the development of closed headphones to use sound-absorbing materials.
An open headset, on the other hand, allows you to actively perceive ambient noise. Accordingly, the design of open headphones is characterised by the fact that they have elements that allow the sound to penetrate the housing. This can be achieved through the likes of sound-permeable materials, or through openings, as in the case of the MMX 330 PRO.