Remove Background Noise with Audacity

Edited by BridgeMix, Anonymous, Jen M, Fleurista and 5 others

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Imagine you just recorded the perfect take, but later when you go back and review the footage you can barely concentrate on the content because the BACKGROUND NOISE IS SO LOUD!!! Wondering what you can do to salvage this recording?

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How To Remove Background Noise

Using The New Noise Reduction Effect In Audacity 2.1

Recording sound has become such a commonplace activity that almost all of us have some experience with it. Maybe you're a student and you like to record lectures as a form of note-taking, or a businessperson that has to record meetings to share with colleagues; or a blogger with a podcast or YouTube channel.

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Often, when we play these recordings back, we notice that the audio quality seems very badly damaged by loud, hissing, humming or whistling sounds that interfere with the dialogue or other sounds we were trying to record. This "background noise" is referred to as Room Tone, and it's caused by all the moving air from drafts in the room, electrical appliances (especially computer and HVAC fans), and other low-level sound sources that our miraculously well-designed ears and brain just filter out when we're live at the scene. Once we play that recording back through, it all becomes plainly obvious, and often intrusive. Luckily, there are digital tools available to help clean up these recordings and restore them to usable quality. There are many excellent programs to choose from, but the Audacity Audio Editor, is a powerful, open source program that:

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  • Doesn't require registration or sign up,
  • Doesn't require an active internet connection to use,
  • Is clean to install,
  • Won't spy on you,
  • Won't give your computer a virus,
  • Works on Windows, Mac & Linux,
  • And it's absolutely FREE for as many computers as you choose to install it on!
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For the latest release (as of this writing), Audacity 2.1.0 made a major update of their years old Noise Removal effect. It's been renamed as Noise Reduction and is much more refined and easier to use with better, cleaner, quieter results. Here's how to use it.

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Install Audacity

Audacity's been around a long time now, and is being widely taught in school systems around the world, but whether you've had your own copy for years or this is the first time you've ever heard of it, the first step is same.

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  • Download the latest version of Audacity from the Audacity website to be sure you have the updated Noise Reduction effect.
  • Installation is pretty straightforward, like most other programs. Basically just click your way through the prompt screens and you'll be ready to go in no time.
  • Add-ons. For a complete installation and full access to all of Audacity's many functions, be sure to visit their Plugins and Libraries webpage to download their various plug-ins, but especially the libraries.
    • If you want to work with MP3's at all you'll need to download the LAME MP3 Encoder.
    • If you want to import audio tracks from video, you'll need the FFmpeg Library. More info on this can found at Extract Audio from a Video.
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Record or Import Audio

Now that you have Audacity up and running you'll need to import the audio recording that requires Noise Reduction.

  • The easiest way to do this is to locate the file in your system, then drag and drop it onto the Audacity workspace. The audio waveform will import automatically.
  • You could also search for the file by selecting File/Import from the top drop down menu, navigate to the file and double click on it to Import.
  • If you don't have a recording made yet, you can just press the Record button near the top left, or R on your keyboard, and Audacity will record a fresh file through your computer's microphone.
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Recording Best Practices

  1. 1
    Make the room Quiet
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    1. Close all Windows, blinds, curtains, and doors.
    2. Turn off all air conditioners, dehumidifiers, fans, fridges, ticking clocks.
    3. Use towels and blankets to cover any drafts and seal the room.
    4. Stand in the room and quietly listen for any sound you wouldn't normally notice and try to eliminate it.
    5. Recording at night is usually much quieter for traffic, aircraft, and other common forms of noise pollution.
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  2. 2
    Microphone Placement
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    1. Every microphone is different, but generally you're off to a good start if you place the microphone as close the subject as possible. This will make the voice sound clearer and less tinny.
    2. Position the microphone slightly to one side or above the subject's face, not in their direct view. This is to avoid pops in the recording caused by breathing into the mic, even without a pop screen.
    3. Aim the microphone at an imaginary space about 12" or 30cm in front of the subject's face to record the sound of their voice in front of them, not their mouth, tongue and lip sounds.
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  3. 3
    Recording
     
    1. Speak slowly and clearly, as if the person you are speaking to is elderly or not fluent in your native language. They might be.
    2. If you're recording in the same room as your computer, make sure the fans are already running for a nice constant background noise. You don't want the sound of fans revving up as this is much harder to isolate and remove.
    3. At the end of recording, completely freeze for 5 seconds. Don't even breath or move or swallow. Totally FREEZE. This is a very important step to get the cleanest recording of any background noise that is present behind your voice, and will serve as an audio fingerprint for the Noise Reduction processing we're about to do next.
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Magnify Waveform

Now that you have your recording imported into the Audacity workspace, we want to magnify its appearance so we can more easily see what it sounds like.

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To do this, simply hover your mouse directly over the 0 (zero) on the vertical scale on the left side of the waveform, it starts at 1.0 to -1.0, and give it four clicks. You'll see the waveform magnify as you zoom in with each click. It doesn't matter if most of the voice recording gets blown out of proportion, we're trying to see the silence, those thin narrow lines between the speech. Once we get the scale to 0.05 to -0.05 we're ready to go to the next step.

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Identify Room Tone

Basically, you want to locate the longest, quietest piece of recording available. If you had the opportunity to record a five second freeze at the end of your recording this is a much easier step. Otherwise, scroll through the recording to try and find the thinnest part of the waveform, hopefully a section of silence 2 seconds or longer. If you're having trouble seeing the silence, hit the play button and listen, and watch as it plays along. You'll quickly be able to zero in on the quietest part. Once you've found it, use the mouse to click and drag a highlighted section over it, preferably two seconds or more. Listen carefully with headphones to make sure there's no extra sounds like rustling that are not caused by Room Tone and adjust the highlighted section to get the cleanest "silence" possible.

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Noise Variations

During your recording, the background noise may have changed. Maybe a fan kicked in and now you have distinctly different sounding silent parts. Just divide these areas by splitting the clip using the Ctrl-I function. We will treat these as separate recordings and reduce the noise separately for each clip.

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Noise Profile

Background noise with a constant quality to it can be digitally fingerprinted if we have a long and clean enough sample, which hopefully we do.

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Go to the top drop down menu and select Effect/ Noise Reduction. Within the popup window, click on the button that says Get Noise Profile. The window will close, and you won't see any changes, but basically Audacity just took a fingerprint of the silence you have highlighted, and has copied it to memory. Now that you have this perfect sample of silence you're ready to Noise Reduce!

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Apply Noise Reduction

Select the area you want to Noise Reduce.

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Hopefully that means the entire waveform track, but if you detected Noise Variations in Step 5 and split the clip, then highlight the clip that relates to the Noise Profile we just took. From the top drop down menu, select Effect/Noise Reduction, and in the popup window click OK.

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If all goes well, this should dramatically improve the recording, but if it's not quite what you had hoped for, Undo with Ctrl-z and let's adjust the settings.

Settings

Every recording situation is different. Even in the same room at the same time of day uncontrollable factors like atmospheric weather patterns can produce different room tone qualities. So listen to the recording and see if you like it well enough. If not, undo with Ctrl-z and adjust the settings again bit by bit until you get it just right.

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  1. 1
    Noise Reduction (dB).
    If you still hear the offending fuzzy static of the room noise you're trying to eliminate, try increasing this slider to increase the amount of noise reduction. Just a word of caution though; as much as you want to mash that noise out of existence, if you go too high you'll end up degrading the voice recording that you're trying to enhance, so just make small adjustments, maybe 4-8 dB at a time until you strike the perfect balance. Pay particular attention to the section of silence you Noise Profiled, areas of speech, and particularly breathing sounds. Some of these parts of the altered recording could end up sounding canny or digitized.
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  2. 2
    Sensitivity.
    If that doesn't work to your satisfaction, try increasing the Sensitivity. This determines how much of the Profile will be considered "noise". Again, don't go too crazy with extremely high settings or you might degrade the voice recording, or introduce digital artifacts that sound like chirps or whistles.
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  3. 3
    Frequency Smoothing (bands).
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    It's rare you'll ever have to go this far, but if you cranked up the previous two sliders then you might want to increase the Frequency Smoothing to get rid of some of the chirpy artifacts that were created. Again, just undo with Ctrl-z and make minute adjustments until you find the right settings. Every situation is different, but this array of sliders are a great example of how powerful and versatile Audacity really is.
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Repeat

If you split the recording into Noise Variation clips, go ahead and repeat this process for each clip.

Check Work

Once you're done, listen to it all together! Check it carefully to see if you want to make any changes, because now is the time, you are about to export!

Export

Go to the File drop down menu at the top and select Export Audio or type Ctrl-Shift-e.

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Choose a name and location and select the file format from the Options button. If you installed the LAME MP3 Encoder in Step 2, then you'll have the option of saving your file as an MP3, otherwise WAV is a universal, high quality standard although at the cost of very large file sizes. Ogg Vorbis is a fantastic compressed format with very small file sizes, though not as commonly recognized. MP3 is somewhere in between.

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Kudos

This very last step is completely optional. Please share this article with your social networks or mention it in your blog, video or website. If you let us know in the comments we can share our appreciation! Thank you!

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Questions and Answers

Remove background music on audacity 2.1.0?

How do I remove background music and leave vocals in audacity 2.1.0

  1. 1
    Open your music file.
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  2. 2
    Copy it with "Ctrl" + "A".
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  3. 3
    Create a new track by clicking "Tracks" > "Add New" > "Stereo Track".
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  4. 4
    Paste your buffer contents into the new track.
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  5. 5
    Select the second track (the new one).
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  6. 6
    Click "Effect" > "Vocal Remover..."
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  7. 7
    Instead of steps 4-6, you can open the same track that you are editing but without vocals, which will be more effective.
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  8. 8
    Select the track without vocals now with "Ctrl" + "A" (the entire track).
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  9. 9
    Click "Effect" > "Noise Removal..."
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  10. 10
    Click "Get Noise Profile".
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  11. 11
    Select the track with vocals with "Ctrl" + "A" (the entire track).
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  12. 12
    Click "Effect" > "Noise Removal..."
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  13. 13
    Click "OK".
    Please note that you can also play with the settings to achieve better results, depending on the track. Your track will be cleaned from the background music as much as possible. It can still have a lot of music, as the vocal remover leaves only the center channel, which is usually dedicated to vocals.
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I have really bad recordings of someone who is no more. I want to make them audible?

I have really bad recordings of someone who is no more. I want to make them audible.. I have tried: Learned about Audacity from net and tried a few steps. It gets better but not to the extent I want.. I think it was caused by: Old recordings

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VisiHow QnA. This section is not written yet. Want to join in? Click EDIT to write this answer.

Hi, I was interested in your suggestion to remove background noise by creating a separate audio track and removing the vocals. How does one get the vocals back without the hiss?

In the 90s, I made a cassette recording of an old record. Now, I am transferring the cassette to an mp3 file. I am getting a whole lot of hiss, and it is interfering with the quality of the entire recording. I tried your suggestion, I tried messing with Noise Reduction and Amplify (- dB on the super fuzzy parts). No success so far. Any suggestions?. I have tried: Oh. I already told you. Oops. I am using a Yamaha tape deck, and I have been able to get other recordings to come out cleanly, so it's not the equipment.. I think it was caused by: The audio was very low, so I used Digital Compression. It might have added to the problem or it might have simply made it more audible. Bottom line: old record, old cassette, lack of skills on my part.

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