I have video footage of an old very sick lady (who has since died) being interviewed. Her voice level is very low. I have been able to bring it up to acceptable levels by using the "normalize" control. However, this has also magnified a "squelchy" (I know very little about sound) background noise (it may come from normal low level noises bouncing around the room). I thought to reduce this by using the Dynamics effects filter, but when I opened it up I realized I was way out of my depth when it came to using the available controls.
What should I do to reduce this background noise?