Hello
I am on windows 7. I’m super novice on audacity. I only use it to “clean” the sound of my videos.
Whenever I reduce noise, and for some time I touch a little bit the parameters during reduction, I always have after the reduction, an echo, a style of metallic robot voice. I do not know how to explain it. Looks like the sound I remove leaves a “void”.
there is a way to touch other things to remove or change the sound of my video?
thank you
That is the sound of too much noise reduction or creating a poor profile in step one. Noise reduction is not intended to reduce noise to zero and it doesn’t work on all noises. It’s best on constant, background noises like computer fans and air conditioners. It will not remove other voices, music or echoes.
What kind of noise do you have?
Koz
And… That’s why pros STILL record in soundproof studios with good low-noise equipment, etc. 
And, that’s why on-location movie dialog is re-recorded in the studio.
Noise reduction is almost always worth a try (if you have noise). Sometimes you can get really good results, sometimes you can only make a slight improvement, and sometimes you have to choose between the lesser of two evils.
You can also try the Gate effect. (Most people call it a noise gate.) A noise gate kills the audio when the level falls below a preset threshold, for example when there is no dialog and only background noise.
Again, that’s something you have to try… It usually “works”, but it doesn’t do anything to the background nose when there are foreground sounds. And, it can be distracting when you hear the background go dead-silent. With video/movies, a noise gate works best if you can apply it to dialog-only before the dialog is mixed with background music or sound effects (so you don’t suddenly get dead-silence).
I have a noise of an empty spaces. Because the record is done with a good micro, with a professional camera, not with the computer or a helmet.
I see. When I try to delete other voices or echoes, I have to reduce the noise to the end and I understand now that is not the right thing to do.
DVDdoug, thank you for your idea, the problem, if I use this solution “Gate” effect, I will only improve the silence and the voice. The problem I get is when I reduce too much the noise, the voice becomes electric
You may not have a working voice track. We can’t take out echoes and we can’t remove other voices. The Noise Gate almost always creates sound damage in the performer’s voice. Nobody ever said, “I rescued my voice into a clear performance using Noise Gate.” Doesn’t happen.
a good micro, with a professional camera
Like this?:
(The fuzzy microphone (dead cat) on the right.)
Koz
The desperation method when a field recording doesn’t go well is to re-record the voices in the quiet studio while watching the video (called looping) and then throw out the field recording.
Koz
Yes like this one.
Thank you for all your advices. even if I bought a professional audio editor like adobe audition for example, the result will be the same, isn’t?
I doubt Audition is going to make any difference.
Voices and echoes are difficult for everybody. Hollywood still shoots in restricted access locations. Crowded street scenes? Usually all those people are actors.
Koz
I have to agree with Koz. There are a couple of high-end VST’s that can do a better job in experienced hands, but they are upwards of a 1.000$…
Look for “audio restoration” if you are considering spending a lot of money 
