The Definitive Guide To Removing Noise From Audio
Did some audio recording and ended up having a noisy recording? You might still be able to save the audio with these restoration techniques, so don’t throw that audio away yet.
Perhaps you had a video recorded and the audio is so noisy that you are looking for how to remove noise from the video.
In this post, I’ll show you a few methods to reduce noise from your audio or video
Before I start with the article, I just want to introduce you to a software called Drum Xtract. It’s a software that helps remove musical elements from an audio recording (usually drums). And can be used to tighten up sound elements within a mix as well. You can read about it here: How to remove drums from a song.
What You’ll Learn
We will go through these few topics:
- How to reduce noise with Audacity for free.
- Remove noise from video recordings.
- Using a denoiser VST with Adobe Audition and other softwares.
- Advanced noise reduction techniques with iZotope RX.
- Best practices when it comes to recording audio outdoors.
First of all, you must understand that it’s impossible to remove 100% of the noise from a recorded audio. It’s not possible. Even if it is, your recorded audio will most likely be unusable, due to the diminished quality.
Many people are also looking for quick ways to remove vocals from audio. While that’s not entirely impossible to do, it usually renders not so good results.
I suggest people who want to remove vocals from music to buy a karaoke version music instead.
Alright, now that you’re ready, let’s go!
Using Audacity To Do Noise Reduction for FREE
Audacity is a popular freeware audio software that runs on the PC or Mac. It’s free.
It’s an amazing piece of software that does nearly everything a good audio editor like Adobe Audition can do. It does noise reduction really well too.
If you’re looking for a quick solution to reduce some noise from one or two audio files, Audacity would be good for you.
Step 1 – Drag Audio Into Audacity
Get your audio into Audacity. This is easily done by simply drag and drop your audio file into Audacity.
Audacity accepts audio file formats such as wav, mp3 and more. For editing, you’ll want to edit in wav. I’ve used an interview audio recording to illustrate the steps to come.
Step 2 – Learn The Unwanted Noise
Find a section of the audio that only has the background audio.
Generally, the longer you can find the better. What we are doing is to select a section of background noise which we want reducing from the entire audio recording.
For my case, I found a fair 1-second background audio in the beginning portion of the audio recording before the interview speech came in.
After selecting, hover over to ‘Effects > Noise Removal’.
Click on ‘Get Noise Profile’.
Doing this actually allows the Noise Removal effect to learn the noise selection you highlighted. This prepares the noise removal software to remove audio.
Step 3 – Reducing Noise
Listened to enough annoying noise yet? Time to remove it.
This time, highlight the whole audio file or select the parts of the audio you want the background audio reduced.
Utilizing the parameters correctly in ‘Step 2’ of the Noise Removal effect can give you the difference in the effectiveness of sound output you get. It’s important to understand them
- Noise Reduction (db): This is how much reduction you do based on the noise profile you captured earlier. I usually go between 10 – 25 to preserve the audio’s naturalness.
- Sensitivity (dB): How sensitive in dB the reduction is done. The higher this is, the more noise it reduces but the more ‘artifacts’ you’ll get in your audio.
- Frequency Smoothing (Hz): This option here is helpful for smoothing out artifacts you hear in the audio. Using the frequency, smoothen out the noise reduction. For instance, if you’re removing lots of low-frequency rumbles, you want to smoothen at the lower frequencies.
- Attack/Decay Time (secs): Controls how fast the audio reduction kicks in and how soon it leaves the audio signal. I normally like a shorter attack time here.
Once you have the parameters set, ‘preview’ the audio file to hear how it’ll sound with the settings you made.
If it doesn’t sound like something you were aiming for, experiment changing the settings a little and then preview again. Once you get a denoising result that you want, click on OK to commit to the changes.
Prefer to watch a video? See how I do it in the video below:
Using A Denoiser VST in A DAW
I use Adobe Audition all the time for noise reduction. Most audio editors have audio reduction effects built in.
Most popular DAWs however, do not have it.
I was mixing audio for a documentary in Logic Studio on a Mac, when i realized I needed a denoising plugin to run inside Logic.
So I started testing noise reduction plugins that are available in the market. Having tried lots of them, I finally settled for iZotope RX. iZotope features a very nice denoising effect that works as a standalone and also as a VST/AU plugin.
Here’s a video of me denoising a noisy interview video using iZotope Denoiser as a plugin in Adobe Audition:
How To Remove Noise From Video
I get this question all the time.
The thing is it’s not that your video is noisy. It’s the audio that was recorded together with your video which is noisy.
There’s no way around it than to invest in a set of dedicated microphones and portable audio record to get good audio when recording videos.
Anyhow, if you already got your recordings, don’t discard it yet. There is still hope of saving them… for now.
I’ll explain how I normally do the job of removing noise from audio.
Step 1 – Find A Way To Unlink Audio From Video
You need to find a way to unlink the noisy audio from your video. This is because you have to edit the audio, not actually the video itself.
I use Adobe Premiere Pro to do this. Adobe Premiere allows me to unlink audio, edit the audio in Adobe Audition and then have it saved automatically after I make changes in Adobe Audition.
Step 2 – Do the Denoising within Adobe Audition
Once you click, ‘edit with Adobe Audition’, Audition will load with your audio file in it. Within Audition, I use can use it’s built-in noise reduction effect to remove the noise from the audio clip.
However, I prefer using iZotope RX Denoiser as it gives me better control over the noise that I want to reduce.
If you don’t have a 3rd party VST plugin like iZotope RX Denoiser, just use the built-in denoiser in Audition.
Once you’re done with the edit, just save and close the program.
Step 3 – Exporting Your Video
Back in Premiere Pro, the audio will be updated with the edits you have made. At this point, you’ll have to export your video, so just re-export your video with the now denoised audio clip.
The Best Noise Reduction Software to Use?
In my opinion, the best noise reduction software in terms of price and ease of use would be iZotope RX.
iZotope RX, since the early days, comes with a multitude of other effects which you’ll find very useful for audio restoring projects. No matter if you’re into broadcasting, audio restoration works or simply a recording engineer looking to clean up your vocalist’s audio files, I guarantee that iZotope will be able to handle all of that.
I’ll briefly talk about the additional software functions that come with iZotope RX.
Note that while the version used in the screenshots below may be an earlier version, the concepts of using it still remains the same.
The difference? Every new version usually has its algorithm optimized to be more efficient in CPU processing and to produce cleaner and higher sound quality.
iZotope RX Denoiser
RX Denoiser works like most noise reduction effects. The advantage that RX Denoiser has over standard audio reduction effects is that it has different algorithms in which you can use to get better results for denoising. It also allows better control over the ‘artifacts’ which are normally left in your audio tracks after you process denoising effects.
In RX 4 you notice a fairly easier interface to use and also an addition of a ‘dialogue’ tab, which gives you more control over denoising audio for dialogues.
RX Spectral Analyser
Spectral Analyser is another effect which can be really useful if you do audio work for broadcast TV.
With Spectral Analyser, you don’t edit on waveforms but on spectral frequencies. This allows you to zoom in into noise audio frequencies and remove sounds, for instance, a single chair squeak during an interview recording. Drops and cuts in audio can also be fixed. The effect accomplishes this by collecting audio sounds around the problem area.
Try it and you’ll notice it’s a little like ‘photo-shopping‘.
Does what its name implies. Removes clipping that happens in a recording.
This effect has saved me many times when I recorded an actor who suddenly screamed in her role, causing my the audio recordings to clip.
RX DeClicker, RX DeHum
Declicker is great when using it to restore things like old tapes and I found DeHum especially useful when trying to repair a concert sound recording which had lots of hum, due to the audio hardware setup.
Best Practices When Recording Outdoors
Having done many recording outdoors at noisy locations and getting into trouble, here is a list of best practices to put in mind when recording outdoors or in situations when noise is inevitable.
- Always record up to a minute of the location. – When I was part of an audio crew, recording a film. We always recorded 1 minute worth of the room noise before we started rolling for real. This gives us a 1-minute noise profile which we can use for denoising audio during post-production.
- Use Shotgun Or Lavalier Microphones – Different microphones work in different scenarios. Shotgun microphones generally give a more natural sound compared to lavalier microphones, but depending on the situation, sometimes it’s wiser to use a lavalier to record audio.
- Invest in Good Isolated Headphones – One of the most important things when recording audio outdoors is to have well-isolated headphones which you can monitor audio from.
- Take several takes – Do as many takes as possible and keep every take whether good or bad. That way you’ll have unlimited tracks which you can cross edit, eventually constructing a clean audio clip.
Did I miss any best practices when recording outdoors and when dealing with noisy audio files? Let me know in the comment box below: