Pop filters are those circular screens that are placed in front of microphones. You often see these in recording studios and podcast studios. They disperse sudden puffs of air that are expelled from pronouncing certain plosive sounds, particularly the letter “p”. Those puffs cause a booming “pop” sound in the mic that is very undesirable on a recording. The screens are made of acoustically transparent material that allows the sound vibration through, but stops the sudden pops of larger amounts of air.
I’ve never seen one used on stage, though. A vocalist on stage is going to pop their p’s just as often as a podcaster in a studio. Why aren’t they used on stage?
A lot of stage microphones are dynamic microphones. These are rugged and often have built in pop filters.
The ubiquitous Shure SM-58 and the like.
In a studio setting there is a much greater choice of microphones, many of which are not rugged enough to see use outside of a studio (ribbon microphones especially.) If a pop filter is needed for a particular vocalist, one needs to be added separately.
A dead cat is slang for the big furry bags placed over microphones when outdoors.They are designed (and quite effective) at removing wind noise. They are not intended as a pop filter, although they will work. They are generally a lot bigger than needed for that alone.
and both of them have some kind of foam screen underneath the metal grille.