I have followed the great tutorial in this site to remove noise from a video clip. However, the end result usually sounds like my actors are inside a can. I think it is called "rumble"?

Is there a parameter that I can manipulate to avoid this?

Thanks!

That's not rumble. It's simply the trade-off you get between noise reduction and remaining audio quality.

First, I recommend you make sure that your audio has a bit depth of 32. Press the F11 key to see and to change if necessary. This will make the noise reduction as accurate as possible.

Second, do your noise reduction in increments. Don't try to remove everything at once. Do modest reduction and make sure it still sounds realistic.

In the Noise Reduction Settings box, you'll see an option to listen to the noise only. If you check this, you will see how much signal is being removed along with the noise. I usually listen to the noise only to get an idea of how much signal I am removing along with the noise.

Third, be satisfied with some noise. As you have found out, the less noise you have, the less desired audio is left as well. So you will have to keep some noise in order to keep some of the audio.

This is a good reminder why it is so important to use the right microphone and microphone technique to get the best sound up front.

If I may ask, what camcorder and microphone did you use? What kind of noise are you trying to remove?

I've found that reducing the noise by 70 to 100 db really helps get rid of that rumble, if the noise is louder than what's on Curt's tut.

Thank you so much, all! I will try these suggestions.
I have a Sony VX2100, and unfortunately, I had to use onboard audio for 4 scenes I shot. I just got an M-Audio Microtack recorder, but I didn't have it for those 4 scenes, I really wouldn't want to reshoot them, so I am trying to salvage the audio.

Thanks!

Generally, this kind of audio is not very salvageable because the broadband noise that is picked up masks the voices very well, making it very difficult for Audition to distinguish between voice and noise.

If this is the unit you got, I'm not sure you'll get much better results. There is no specification of the microphone's pickup pattern, which tells you what sounds it accepts and what sounds it rejects.

What you really need to get is a shotgun microphone, which rejects a lot more noise than your onboard microphone and most likely your M-Audio unit. Search these forums on "shotgun microphone" to get lots of discussion on this topic.

I will. Thanks, again!!