Taping people in less than ideal conditions, like echo-y conference rooms and hallways, I've fast learned that hum, echo and background noise are a fact of video life. For example, what is it about taping a person talking in a quiet room that attracts construction workers to begin throwing large chunks of scrap metal into nearby dumpsters?

Hum is almost unavoidable in some situations, with fluorescent lights and forced air contributing about equally to the din.

When given another such project, I asked one of the local experts how to reduce hum. He suggested getting a little Mackie mixer and EQ'ing out the hum, especially if it were generated by ground noise or some machinery. But then finished by saying "fix it in post." He mentioned that it is easier to notch hum out if the speaker is female, because the voice is mostly much higher than the frequency of the hum.