Help with Noise Removal

Audacity Help Forum Windows
1

I’m having problems getting rid of the background noise in wav files

I’ve been trying a number of different settings on the noise removal effect

When I slide noise reduction down I get left with a lot of snow, but if start getting high, the snow goes away, but then I get something that sounds like wind wheezing that gets loud when there is voice.

I’ve also moved the other sliders but haven’t been able to get rid of the noise.

I was given a whole directory of these files to “edit and clean up”. They are instructional audio, I work in a school.

Using Windows 7, Audacity 2.0.1 from installer

I’ve attached a part from one of the files

Hope someone can get rid of the noise. Also, please tell me the steps. I’m new to audacity and editing audio.


Thanks.

2

You have two problems with that clip. There is hum/buzz from possibly a bad microphone cable and there is also hiss from possibly a bad microphone preamplifier. Under the best conditions, we can produce a show with quiet spaces between the words, but noisy words. Also, once you remove the noise, it turns out the person talking may have been too close to the microphone.

This clip used the “dead” area at the beginning as the Profile and then applied the profile with Reduction-18, Smoothing-150, and Attack-0.1. I think that’s the best that can be done.

Koz

3

Drag-select a portion of the show with noise only. No voices. Effect > Noise Removal > Profile.
Then drag-select or just select the show you want to clean and Effect > Noise Removal > Set the Sliders > OK.

That’s the two sentence version of Noise Reduction.

Koz

4

Thanks Koz.

That’s what I was afraid of.

I just told my boss that and got an evil look and said something about high and low pass something. Not sure if he knows what he’s talking about but I guess I don’t have a choice but try and tinker around with it and give him a few choices to listen to.

5

You can absolutely turn it into a telephone call with the high and low pass filters. You can simulate that with Effect > Equalizer like this…

http://www.kozco.com/tech/audacity/pix/telephoneFilter.jpg

Professional recordists also use a less dramatic series of filters – the most common one is High Pass Filter set to 80, 100, or 120 Hz. The sound gets tighter and more gutless as you go up. Low Pass Filter set to 5KHz will make the show sound like an AM radio.

None of them is going to affect the interference. My settings may be the best you can do. I posted a note to the other elves to change the name of the tool from Noise Removal to Noise Reduction because too many people think it’s a magic carpet to making a trashy recording into a studio presentation.

It’s not.

One joke is to use the tool when you don’t need it and by the time you think you need it, it’s too late.

Koz

6

The odd whomping noises during the words I suspect are the performer too close to the microphone. Nobody can cure that although you might help with the 100 Hz High Pass Filter.

Many of us would be shooting that show again correctly.

Perhaps your boss can show you how it’s done.

Koz

7

  1. Equalization
    eq.png
  2. Notch filter at 60, 120, 180, 240, 300Hz.
    You can do this by using the Audacity Notch filter 5 times. I did it using this code in the Nyquist Prompt effect (just once):
(notch2
  (notch2
    (notch2
      (notch2
        (notch2 s 60 1)
        120 2)
      180 4)
    240 8)
  300 16)
  1. Noise Removal effect:
    Reduction: 15
    Sensitivity: 0
    Smoothing: 150
    Attack: 0.1