Better Muffing adds one block, the Muffling Block. This block muffles sounds nearby. As well as in the minecraft settings, the sounds are grouped in categories. Each category can be adjusted in the gui to reduce the volume of the sound category, as well as the range can be adjusted based on the config settings. With the private mode on, only the placer of the block can adjust the values.
If you found a bug or have a suggestion please use the Issues tab on the github project.
Fell free to use this mod in your modpack. I would love to hear in which modpack you are gone use it, so just send me a short message :)