Pop filters, reflection filters
A pop filter can be essential if you are singing very close to the mic and are producing lots of “P” and “B” sounds. These sounds produce a lot of air and briefly overload the sensitive diaphragm of the microphone. To counter this, the membrane of the pop filter slows down these burst or ‘plosives’ to lessen the impact on the diaphragm.
A reflection filter is an object that (in principle) lessens the amount of unwanted reflections (or echo) from a bad sounding room. You might think that you can’t hear any echo as the traditional notion of an echo is that of the cartoon character in the mountains shouting and hearing himself back many times after. The type of echo we are worried about here is nothing like that. They are called ‘early reflections’ and can be imperceivable as a traditional echo. This is because as the name suggest early reflections occur so quickly that, to our ears they appear to be part of the original sound, and in a bad sounding room this could really colour what could be a very nice original sound.
For a home studio the colorization of the recorded sound is a huge factor why sometimes we dont quite get the sound were looking for. Here is an example of two recording of the same instrument play by the same player in two completely different rooms.
They arrive later than the direct sound, often in a range from 5 to 100 milliseconds, but can arrive before the onset of full reverberation. The early reflections give your brain the information about the size of a room, and for the sense of distance of sounds in a room.