This mod overhauls and expands the Falmer "dialogue" by replacing the regular grunts, shrieks and nondescript noises with a more subtle sound, known as Echolocation.

Echolocation is the process in which an animal obtains an assessment of its environment by emitting sounds and listening to echoes as the sound waves reflect off different objects in the environment.

The objective of this mod was to make the Falmer sound more feral, and with so many generations of them being blind, they have adapted to use echolocation as a means to track their prey and to better navigate their surroundings. They now sound like they are truly incapable of making noises more than a splutter or gurgle.

Expands on Falmer dialogue by adding lines based on what's happening. Falmer will now make idle "click" noises, intended to be them finding their way through their environment. They also now make alert noises if they detect an enemy nearby, or they make more aggressive sounds and clicks if they have found an enemy. In addition, Falmer can now "taunt" their targets, as a way of them alerting each other to where their target is.

This is all done using a custom quest, and as of v1.1 it should now be fully compatible with custom creature mods that also use Falmer SFX, as the new version does not replace any vanilla dialogue.

I feel like a mod such as this one should be experienced first hand, but here's a poorly made video if you really want to get a feel for it