This popscreen is an anti-pop noise protection filter for mikes ,typically used in recording studios.It serves to reduce or eliminate 'popping' sounds ,like words with "T" and "P' in them(plosives) and "SSS" (sibilants)caused by the mechanical impact of fast moving air on the microphone during recorded speech and singing.
It also keeps moisture off the microphone which can cause elemnt corrosion and also altering the mic's sensitivity and response. Salts in human saliva are corrosive and thus use of a pop filter may improve the life of the microphone.
