Hi, I wanted to know if we are allowed to use assets from the game we have chosen.

In my case the game has a background noise of a city (so just wind, train, ...) and it would be annoying (and impossible for me) to make it by myself. It is not a music and I guess it has no copyrights, it's just some city noise.

And if we are not allowed, are we allowed to use assets if we modify them ? For example, changing a sprite, changing a sound effect to sound older.