Replacing Noise with Room Tone

I am using Audacity 2.3.2 on a Mac with OS X 10.14.4

I am working on a video I shot back in 2012 using a low quality camera’s microphone. I ended up with a horrible screeching sound that sometime appears on its own but some times appears simultaneously with the talent’s dialogue. The screeching sound is horrible. My first attempt at noise reduction back in 2012 was a disaster, in that it damaged the dialogue considerably.

The video has considerable sentimental value. It is a family member telling her life story. She is very old and she is in no position to redo dialogue.

I prepared a short clip with the screeching sound and have posted it as an unlisted video. If you want to see what it sounds like you may view it here:

To mitigate the noise I have been doing two things:

i. Where the screeching sound appears alone, I replace it with room tone; i.e. a segment of the video that is relatively quiet.
ii. Where the screeching shows up simultaneously with dialogue, I use the noise reduction effect on these specific segments. It doesn’t work so well with this kind of noise, but i do not know what else to do.

Wherever I find the screeching sound on its own I want to replace it by room tone. I tried replacing the bad segments with “white noise” or the other noise options generated by audacity, but they sound weird. They are not natural and do not go well with the rest of the audio file.

Notice also that I want to keep the present timing. Cut and paste will not do because it would alter the timing of the audio file.

What I have been doing to replace the screeching sound is the following.

1 Identify a range that contains the noisy segment in isolation.
2 Press Command B to label the segment.
3 The label should appear in a separate track designated for labels.
4 Create yet another track below the label track. Copy the room tone (from the main sound track) and paste it in this third sound track. It should have the same size as the main sound track (e.g. mono or stereo).
5. You will need to move this segment of room tone in its separate track to position it below the label track at the specific point where the noise starts in the track being edited.
6. Next, use the label borders in the label track to select a segment of room tone that is equal in size to the noisy segment in the track being edited. You can (sometimes) tell that it is of equal size by the fact that yellow borders appear when the main sound track region is matched. 7. Select the noisy segment in the main track, making sure your selection matches the label boundaries. Then paste your room tone.

Clearly this is a very time consuming process. I wonder if there is some other way of replacing noise with room tone without affecting overall timing of the clip, that is faster and easier to apply.

Your help is appreciated.


It’s not a good idea to go back and edit a post. Sometimes we remember your first post and come back later to answer it. If you change the post, we might be answering the wrong question. The forum software will warn us if you make a new post so we don’t miss anything.

I would leave the noise that occurs during voice alone. I don’t think it’s as bad as you say and most people are going to bond with the woman, even with noises. A clear, unblurred video will let us see her lips and help fill in the missing parts.

That and I don’t think you can use Audacity tools to separate the noise.


As you may have seen by now, we can open up the sound track from many different video types, but we can’t put the corrected sound back. for that you need an actual video editor program.



What you say makes sense.

I am using Final Cut Pro X as video editor. After I reduce the noise that occurs on its own, I sync the repaired audio to connect with the video. This is why I can’t alter the audio’s timing.