Counter-Strike 2 Workshop Tools/Audio Blocker
Audio Blocker is a texture that muffles sound based on the placement of the mesh with its faces textured with Audio Blocker and your Line of Sight "through" it to where the origin of a sound is.
Examples
Map with two floors, it can be useful to muffle audio between the two floors. This is where a mesh with Audioblocker on it can come in handy.
This example has an audio blocker mesh that covers the entire ceiling of the first floor.
Without the audioblocker mesh, if you threw a Molotov on the second floor and were standing on the first floor you would hear the audio as if you were standing close by.
With it, if you throw that same Molotov and are in a position where your line of sight to the Molotov's origin is blocked by the AudioBlocker then it will result in a muffled audio of the Molotov rather than the full volume version like before. If you move to a point where your LoS is no longer blocked by the AudioBlocker mesh than you should be able to re-hear the unmuffled Molotov audio.
Note:It's recommended to play around with the area of the mesh when near stairs or areas where you can go between floors with audioblockers in between them. This is because the AudioBlocker mesh may inadvertently muffle audio, such as the Molotov in this example, even if under normal circumstances you would be able to hear it fine.It may also be helpful to look at de_Nuke for an example of how Valve used this (Shown below using 
).
On Nuke, Valve put a BlockSound mesh underneath most of the maps ground mesh and left decently large gaps in it around areas where the player would transition to the lower level of the map.
Differences between AudioBlocker and BlockSound
Currently not known what the real difference is between these two textures. AudioBlocker has the "audioblocker" PhysicsSurfaceProperties and a CollisionProperty of "no_collision_block_sound" while BlockSound does not but does have the attribute "mapbuilder.blocksound" "1".
