|Note: This feature is only available on Windows systems.|
The reverbedit console command allows to create REVERBS lumps in real-time. Using reverbedit will set the game in windowed mode automatically if you were playing in full-screen. Using alt-tab or by calling up the menus to free the mouse cursor, you can shift the focus from the game window to the reverbedit windows and fine-tune settings, then you can move back to the game window to listen to the result, unless you uncheck the "test in level" checkbox.
Although reverbedit does not let you change already-defined environments, you can create new ones based on an existing one. Once satisfied by the result, you can click on "save" to write the desired environment or environments to a text file which you can then use as a REVERBS lump.
Hitting the "escape" key or clicking on the "done" button will close the reverbedit window.