The quiet_nightvision.zip file you have requested: Clear Sky / Mods / Sound and Music / Quiet Night Vision - 4.14kb is not available. Perhaps try browsing all files for the game S.T.A.L.K.E.R.: Clear Sky and upload any files you want to share or are missing. This is the only information we could locate:
This mod is a simple fix to the annoying "beeping" night vision enhancements make while active. Night vision still functions normally otherwise and still has a power up/power down sound for realism.