The mesh on headphones and earphones is a metal wire filter that stretches over and around the speaker to provide an acoustic filter and protect the driver from damage due to sweat and moisture.
It also keeps the speaker securely in place, so it doesn’t move, which can distort sound quality if not prevented.
An in-ear headphone’s metal mesh on the front output tube dampens its resonance from 4 to 8 kHz.
Removing this mesh will enhance this resonance, increasing sound quality, but it will also expose the driver inside to sweat and dirt, which can cause damage later on.
The primary purpose of the mesh is to keep dirt and other things away from your earbuds.
It can be made of plastic or metal. Plastic mesh screens are only seen on cheap $1 use-and-throw earphones. Most headphones and earphones come with a metal mesh.
Plastic cannot be as fine as metal to protect what lies inside from small debris.
It also isn’t as flexible as metal, which can be a significant problem when cleaning them.
You can definitely use the earbuds without the mesh, and you may actually get a new musical feel afterward.
Just remember that this makes them far more prone to damage and that there is nothing to protect the sensitive internal components.
If you cannot hear the difference between the sound with and without the mesh, don’t worry, as the difference is minimal.
Overall, using headphones or earphones with a mesh screen is always better.
Are you interested in knowing the role of small vent holes in earphones? I have written a small and exciting blog post on that topic.