weird sound after noise removal in audacity

[happydog500]

I have a talk I recorded (digital recorder a few feet from a speaker) and have some noise from a little bit low signal. I removed it in audacity. I know if you do to much removal, it will affect the sound. I tried several different settings, including all the way to "less." I get a weird noise that is wrecking the recording.

I get this on other recordings I've done, so it's not this recording, but audacity. I have read that this can happen in audacity when you use to much noise removal, but with going all the way over to less, I thought I would avoid it.

Is anyone familiar with this? What can I do?

Chris.

[redwudz]

What filter or modification did you use with Audacity? You might also better describe the 'noise' and someone may suggest the proper filter. Another alternative is to post a short representative sample of your problem audio file here and others may have a better way to filter it.

[happydog500]

Here is a sample of the noise after I used noise reduction. This is the same thing I always get when I use it.

noise.wav

noise%20before%20noise%20reduction.wav

[Soopafresh]

Typical sound artifacts of too much noise reduction. Try to EQ to reduce the hiss rather than run NR.

[jagabo]

Typical sound artifacts of too much noise reduction. Try to EQ to reduce the hiss rather than run NR.

I agree.

[happydog500]

Typical sound artifacts of too much noise reduction. Try to EQ to reduce the hiss rather than run NR.

Why would it be to much if I used the least amount possible?
Thanks for the input,
Chris.

[jagabo]

That noise reduction filter is for patterned noise -- like a continuous buzz, not for random noise like a hiss.

[happydog500]

That noise reduction filter is for patterned noise -- like a continuous buzz, not for random noise like a hiss.

That's what it is, a continuous buzz all the way through the recording.

I did some testing with the EQ. The Buzz is in, from before halfway, all the way to the high end. I'll keep trying,
Thank you,
Chris.

[lordsmurf]

I've created counter-filters to fight off audio artifacts caused by "too much" processing. Remember the goal of restoration is to MAKE IT BETTER, not MAKE IT PERFECT. You must pick between the lesser of evils.

[happydog500]

Why does someone make a program where the least amount is to much?

[Soopafresh]

Good question. It's really because you're not using the right tool for the job.

There's a great free VST plugin called Floorfish which can work on a hissy source by using dynamic range expansion and noise gating. Takes some practice to figure it out, however.

http://www.digitalfishphones.com/binaries/the_fish_fillets_v1_1.zip

Here's your noise clip. That Niagara Falls drop at 8000Hz says the source was probably an Mp3 or Mp2 compressed file. Between 4200Hz and 8100Hz you see an increase in volume, which is probably where a lot of the hiss comes from. Anything above 8130Hz is high frequency crackle. So with an aggressive EQ, you can cut between 7600 and 20000. Anything below 80hz on the low end of the spectrum is probably rumble and can be cut as well. The tricky bit is reducing the frequencies between 4200 and 8100Hz without affecting the overall sound too much. Experimentation will be required in that area.



Here's an example of EQ run against your noise file. You'll hear the before and after every 1 second.

eq_example.wav

[jagabo]

You should also provide a source with some of the speaker too. Anyone can reduce the noise in your sample by just turning down the gain. Of course, that would eliminate the speaker too.

[mpack]

I have to say that audio is a real weakness of mine. I've been working on bitmapped images for 25(?) years and feel I have a deep intuitive grasp of them in all their variants - but I can't say the same about audio. I have no problems working to clean up a video source, but I'm lost when it comes to cleaning up audio.

As a programmer I do have a technical understanding of the maths (and the code) behind FIR, IIR, and FFT - but I lack knowledge of how and when to apply it, eg. I have no real idea of what causes hiss or how to get rid of it without causing the chirpy cheep cheep artifacts.

I've tried buying books on the subject, but they've been universally awful so far: DSP books that teach me how to synthesise a choir of bells (I'm not trying to create music), "All About Audio" books that tell me how to build my own sound studio. Does anyone have a recommendation?

[happydog500]

Here is a clip with the speaker talking. As you can hear, the noise is distracting.

clip%20with%20speaker.wav

[AlanHK]

I have a talk I recorded (digital recorder a few feet from a speaker) and have some noise from a little bit low signal. I removed it in audacity. I know if you do to much removal, it will affect the sound. I tried several different settings, including all the way to "less." I get a weird noise that is wrecking the recording.

Which version of Audacity?
The built-in "noise removal effect" is much better in the 1.3.5 "beta" than the 1.2.6 "stable" version.

PS -- I loaded your last clip and applied the effect with 17 dB of reduction. That got rid of a lot of hiss, the voice got a little "underwater" sounding, but better than the original. If you spent longer experimenting I'm sure you could get a decent result.

[happydog500]

I have both the stable and beta. The beta keeps crashing, so I used the stable. I did get a little better with the EQ.
In the stable, noise reduction has one thing. In the beta, it has 3 I think. I'm not sure what the other 2 things do.
Thanks for the replies,
Chris.

[AlanHK]

In the stable, noise reduction has one thing. In the beta, it has 3 I think. I'm not sure what the other 2 things do.

See http://audacityteam.org/wiki/index.php?title=Noise_Removal#Improved_Noise_Removal_in_1.3.3

[SLK001]

How does one go about posting an audio clip? I have the audio with the noise mostly removed that I would like to post.

If there is an audio clip below, don't bother to respond.

[SLK001]

Another attempt:

[SLK001]

Okay, so how do you post an audio clip?

[jagabo]

Zip it up. Then use the image upload.

[happydog500]

I don't zip mine up. I save the file, the "brows" button at the bottom, find the file and it posts.

[Soopafresh]

It'll work as long as the files is < 6MB

[jagabo]

I've had trouble with some file types (forget which). I upload them and they disappear. So I zip them up and upload again. That always works.

[SLK001]

It'll work as long as the files is < 6MB

It's only 2.9MB, so it should have worked.

Here's an attempt to upload the file as a .ZIP file.


I give up... Just copy this to a new browser and it will download the file.

https://forum.videohelp.com/images/guides/p1893010/speaker(improved).wav

[SLK001]

What, no response from the OP?