Reverb is how your brain knows it’s inside a cathedral instead of a closet. Every surface a sound bounces off adds information — the size of the room, what the walls are made of, how far away you are from the source. Artificial reverb is the art of faking these cues, and each method fakes them differently.
Watch the density: Room reflections arrive quickly and close together because the walls are nearby. Your brain interprets this dense cluster as "small space." Increase the size parameter and watch the early reflections spread apart — the room grows around you. Decrease damping and the tail brightens, like switching from carpet to hardwood.
Reverb is the oldest audio effect — it predates recording by thousands of years. Cathedrals were the first reverb units. Gregorian chant evolved to exploit the long decay times of stone architecture: slow, sustained notes that let the room become part of the instrument. The music shaped itself to the space, and the space shaped itself to the music.
When recording moved indoors to dead, treated studios, engineers immediately started trying to add the space back. First with chambers (real rooms), then plates and springs (mechanical systems), then algorithms (mathematical models). Each one captures a different slice of what “space” means to the human ear.
The progression tells you something about what reverb actually is. It isn’t an effect added to sound. It’s the sound of where you are. Every reverb algorithm, no matter how abstract, is an answer to the same question: what does it feel like to be in this place?