When you record vocals, a vlog, or a podcast in a less-than-ideal condition, you are bound to get some noise from your equipment and room. This article explains the best free and paid methods to remove background noise from an audio recording.
Noise reduction isn’t a click-and-go process that many would lead you to believe. Sure, some programs claim to make it so, but some manual work combined with software gives you the best possible outcome. Hence, we will be providing you with everything you’d need to know to create clean recordings.
So, let’s get right into it! First, we will be talking about noise in general, why it happens, and its types. Then, we will talk about the methods you can use to reduce every kind of noise. Finally, we will end with some tips to help you prevent background noise in your recordings in the first place.
What Is Background Noise?
Background noise is anything you hear in your audio recording other than your voice or instrument. Most commonly, you will find a hissing noise in your recordings caused by recording equipment. Other times, it could be the sound of your room’s air conditioner or your neighbor.
What Types Of Noise Are There?
In general, there are internal and external noises. Depending on the noise source, you will notice a different kind of sound, and each requires a different type of treatment. You can prevent some of them fairly easily, whereas others require you to buy equipment and so on.
Furthermore, in our article, we have several methods for noise reduction. Hence, each of the types of background noise described below will comment on whether you can fix it during editing. And if yes, we will also mention which of our techniques will be the most appropriate for it.
Internal noise is the noise caused by your recording equipment or power supplies. These often last throughout the entire audio recording, but there are cases when they also disappear over time. We will be delving into the various kinds of the internal noise in this section:
- Mic Noise
Reduction: Method 2
The hissing noise caused by mics is probably the most common issue with audio recordings. There is no permanent cure for this type of noise other than replacing your mic. However, the noise reduction methods we will cover in this article can help you with this problem.
The audio demonstrates a condenser mic’s self-noise in an isolation chamber.
- Audio Interface/Chip Noise
Reduction: Method 2
Albeit less common than mic noise, both share very similar characteristics: hiss. Simply disconnect your microphone and hit record; if you hear the hiss, all the same, you have a poor audio interface. As with mic noise, noise reduction will help. However, if you intend to replace your audio interface, here’s a handy guide.
- Electromagnetic Interference
Reduction: Method 4
We live in a world full of electromagnetic waves emitted by phones, Wi-Fi, lighting circuits, and Bluetooth devices. They create a particular kind of noise that distorts the audio signal and sounds like gated synths. Unfortunately, it’s pretty much impossible to fix it while editing, other than by chopping off the damaged parts.
The audio demonstrates audio being disrupted by radio signals.
- Electrical Hum
Reduction: Method 1
Some electrical components add audio humming in your recordings caused by an electrical power supply. Generally, if some part of the A/C enters a D/C circuit, you will hear a low-frequency humming, which is solved by adding a grounding connection. These can be eliminated in editing as well.
The audio demonstrates a humming caused by the lack of a grounding system.
External noise (or ambient noise) involves real-world noise that gets picked up by the microphone. Often, these appear in short bursts and disappear. Of course, noise caused by an AC, for example, lasts throughout the recording. Let’s talk about the various kinds of external noise:
Reduction: Method 4
If you are recording outside, the wind can be pretty loud. You will want to invest in a windshield (or windscreen) to solve this problem. Unfortunately, there isn’t much you can do during editing to eliminate wind noise.
The audio demonstrates the sound of wind recorded without a windshield.
- Room Appliances
Reduction: Method 1 & 2
A hum from an air conditioner, fan, or PC is a common issue in recording indoors. Of course, turning off the appliances is the ideal solution, but you cannot turn off some devices like the computer itself during recordings. These can be reduced using our editing methods.
Reduction: Method 3 & 4
There are several other kinds of noises like sounds from your neighbor, machinery, mechanical noise from your setup, and so on. They produce short noises that may or may not be mixed with your voice or instrument. If mixed, use Method 3, whereas Method 4 is for the noise that hasn’t mixed with your voice/instrument.
Methods Of Noise Reduction
Depending on the kind of noise you are looking to reduce, you can select from one of the following noise reduction methods. Most methods have more than one way to achieve the effect. So, we will provide a free and paid alternative. Let’s get right into it.
This method focuses on humming that is generally not affecting your audio. Hence, we will be using an EQ to remove parts of the frequency spectrum affected by the noise. We will be using FL Studio and OcenAudio for demonstration.
You can download OcenAudio here.
- Step 1
Use a frequency analyzer (some EQs have built-in analyzers) to identify the problematic frequency. Simply playback the recorded audio looping over an empty part where you aren’t speaking/playing, and note the analyzer. The peaking (tall) part is the hum; so, note that the frequency (labeled at the bottom of the graphs below) is close to 100 Hz.
- Step 2
The easiest way to get rid of such a humming is to EQ it out. You can do so only when the frequency doesn’t overlap with your voice/instrument. Add an EQ band over the peaking frequency (95 Hz in our example), and set its shape to a notch filter. You can also use a peak filter to reduce the gain if you aren’t looking for an extreme result.
- Step 3
Confirm what you are removing is the hum alone. Adjusting the Q factor or, in OcenAudio’s case, the Passband limits will allow you to narrow down the filter precisely over the hum only. Doing so avoids artifacts over the rest of the frequency spectrum.
- Step 1
When the noise is complex and spread throughout the frequency spectrum, you cannot isolate it using a simple EQ. So, this method uses an automated process called Noise Reduction, which can remove even the noise over your vocals/instruments. Therefore, it is the most universally effective method on our list.
Unfortunately, an extreme amount of noise reduction will introduce artifacts in your audio. So, you’re better off limiting its usage over short parts of the audio. A point worth noting is that some software products are better at noise reduction than others. For example, neither FL Studio nor OcenAudio can provide you the level of flexibility that much more expensive software like Izotope RX-8 does.
- Step 1
Make sure your audio editing software supports noise reduction. Do an online search for “noise reduction your_audio_editor” and see if you can find a mention of “noise profiles,” “noise reduction,” or “denoiser” feature anywhere. The following audio editors provide this feature:
- FL Studio’s Edison
- OcenAudio (free)
- Audacity (free)
- Steinberg WaveLab
- Magix Sound Forge
Since we cannot focus on every audio editor, we will use FL Studio and OcenAudio alone. However, almost all software uses similar terminologies, so you should be able to follow the steps reasonably easily.
- Step 2
For the denoiser to work, it needs to “listen” to the noise and create a noise profile. So, select a part of the audio where there is only noise (no voice/instrument), then click on “Get Noise Profile” or something very similar.
- Step 3
Finally, you can go ahead and adjust any settings available. For example, the FFT Size in OcenAudio adjusts how fine-grained the noise profiler is (bigger number equals better quality). Then, apply the noise reduction.
Our third method is manual spectral editing. Now, spectral editing is the same technology that our previous method uses. The difference is that we will be manually editing out the noise instead of letting the software detect the noise and automatically edit the audio.
Spectral editing means any sort of editing that is done to a specific range of frequencies. If you are familiar with multi-band compressors, then you are already aware of it. For our editing, we will be using a software called ReaFIR, which is available for free.
This method uses the analysis step from Method 1, so make sure you have read it already.
- Step 1
Analyze the noise using an FFT Analyzer to determine the exact frequency of the noise (Step 1 in Method 1).
- Step 2
Load ReaFIR in your audio track if you are using a DAW. And if you are using an audio editor like OcenAudio, find ReaFIR under the Effects>VST menu.
- Step 3
In ReaFIR, set up the parameters as follows:
FFT Size: As high as your CPU can handle.
- Step 4
You will notice a horizontal on the graph in ReaFIR. Only the sounds above this line will pass through ReaFIR. So, right now, you will hear nothing. Hold Ctrl on your keyboard and drag down with your mouse to bring the line to the bottom.
- Step 5
Create a peak precisely in the area where the noise is (according to the frequency analyzer from Step 1). Make the peak high enough to reduce the noise but not so high that it reduces your voice/instrument as well. You’ll have to make a few tries to get it right.
You can also use a dedicated spectral editing tool such as REAPER or Steinberg SpectraLayers 7 to achieve even better results. However, note that these programs have a relatively steep learning curve.
Here is our final method, where we will be using a gate to eliminate all the sounds below a certain threshold. This method is only applicable when the noise is in-between your voice in your audio recording.
- Step 1
If you are using a DAW, place a gate in the first place of your effect chain. And if you are using an audio editor like OcenAudio, find Gate/Noise Gate under the Effects menu.
- Step 2
Adjust the threshold so that only the noise is affected while the rest of the audio remains playing. You can also adjust the attack and release to make the transition smoother. The attack controls how quickly the gate applies, and the release controls how quickly the gate stops working.
- Step 3
If you are using an audio editor, click on Apply. And if you are using a DAW, you can either render the audio out or let the gate plugin work in real-time.
How To Remove Noise Using Audacity?
Audacity has a built-in effect plugin that denoises automatically based on a noise profile analysis. Select a part of the audio with the noise, open the Noise Reduction effect, and click on Get Noise Profile. Next, select the area where you want the noise reduced, reopen and apply the Noise Reduction effect.
As a lot of people are using Audacity as their primary audio editing software, here is a step by step guide showing the Method 3 process in Audacity:
- Step 1
Select a part of the audio with the noise. Go to Effects and find Noise Reduction.
- Step 2
In the Noise Reduction window, click on Get Noise Profile. The effect plugin will analyze the selected area and recognize it as noise. As soon as you click on the button, the window will disappear; this is normal.
- Step 3
Select the area from where you want the noise eliminated. Typically, this area is over your vocals/instrument. Then, reopen the Noise Reduction effect plugin.
- Step 4
Adjust the various settings. You will generally want a high amount of noise reduction (upward of 10 dB) and keep the sensitivity around 5. Use the Smoothing feature if your audio has audible artifacts after noise reduction. Before you hit OK, make sure to use the Preview button to listen to how it sounds first. And the Residue button allows you to listen to what has been reduced from your audio (the noise). It’s handy to listen to how much of your voice/instrument is being affected.
Tips For Noise Prevention
While having multiple methods of removing background noise is excellent, it’s a good idea to know how to avoid it in the first place. The reason is that noise reduction always comes with artifacts; you will change the fundamental sound of your voice/instrument along with the noise itself.
So, here are six tips for you to help prevent noise early on:
- Recording Equipment
Consider purchasing a decent microphone and audio interface to improve your recording quality. You can also buy a budget USB microphone or a portable audio recorder like the Zoom H1n, both of which are much better than a phone/laptop mic. Their prices range around $100 and above.
- Microphone Gadgets
Depending on your recording circumstances, various gadgets can help you reduce background noise. For example, a fleece windshield is handy when you are recording outside. Similarly, a pop filter eliminates plosives when you say p or b. And a shock mount will reduce vibrations when you touch the mic stand or your table.
A grounding system adds a low impedance connection to the earth so that rogue electric charges can travel into the ground and not harm you or your gadgets. While most countries have mandatory grounding systems, some countries don’t. So, if you live in a house without a grounding system, endeavor to have one for safety and noise reduction. Here’s an article explaining the concept of grounding.
When you are recording, use balanced cables to connect your mic to your audio interface or PC. Balanced cables provide protection against electromagnetic interference and audio loss. So, they are also helpful when you need a longer cable. The only downside is that they can be relatively more expensive.
- Room Treatment
The acoustic treatment eliminates the reverb and echoes in your room, which adds clarity to your recordings. While professional treatment is often costly, you can combine wooden furniture, carpets, mattresses, and acoustic foam for decent results on a budget. You can also build acoustic panels using Rockwool if you are into DIY projects.
- Quieter Appliances
Sometimes, essential appliances like the fan or even a PC create a lot of background noise. The easiest way to reduce ambient noise is by opting for quieter appliances—for example, a bladeless fan for your room and a quieter cooling system for your computer. And if you have the budget for it, replacing your hard drives with SSDs is ideal.
While recording audio, you will encounter many kinds of background noise and artifacts in your recordings. However, knowing the various methods of noise reduction can help you solve each with ease. If you are only starting to record audio, we suggest learning to prevent noise early on.
Similarly, another useful skill is masking noise. Let’s say you are recording guitars for a hard rock song, and you notice a hiss. However, the chances are that the hiss won’t even be noticeable in a full mix. Further, you can use EQs to make noise even less apparent.
Of course, if you wish to look into more advanced noise reduction solutions, plenty of software products are available. iZotope RX8 and Acon Digital Audio Restoration Suite 2 provide the most comprehensive audio repair solutions. And Klevgrand Brusfri is another simpler denoiser that offers outstanding results.
That isn’t to say that free tools or stock plugins are poor, though; they often provide results exceeding expectations. So, even if you are a professional recordist, make sure you give them a try.
And that brings us to the end of our article. We hope this guide has been helpful for you to achieve a cleaner audio recording.
K. M. Joshi is a multi-award-winning composer and sound designer, specializing in film, game, and TV audio. He enjoys making cinematic music, rock, blues, and electronica.