I'm guessing for a comedic performance, the SPLs weren't blaring. So could be a combination of the causes mentioned, but I'll also throw in your gear's self-noise as a potential culprit. What gear are you running?
At any rate, you might try the noise reduction options in your favorite WAV editor to minimize the effect. I find I'm more tolerant of NR impacting the main source (the voice) for spoken word recordings v. music.