One of the most useful tools at your disposal when recording any kind of audio – music or voiceover – is good noise reduction. I wrote a post about the hidden noise reduction tool in Reaper that is actually just one function of a filter that comes free (along with dozens of other effects) with Reaper (www.reaper.fm), called ReaFIR. That post, along with the associated video, is: ReaFIR Madness – The Hidden Noise Reduction Tool in Reaper.
I made some wise crack about FIR standing for something technical and inscrutable. But in fact, Finite Impulse Response (FIR) is a type of digital audio filter with several uses to help you fix, enhance, or otherwise alter your audio. Here is an article that, along with its predecessor (the article, not the filter) about infinite response filters (IIR):