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10 Types of Noise in Audio and how to Get Rid of it for Good

Noise is an inevitability when recording in an untreated space or with budget equipment. But what are the different types of noise?

Noise comes in many forms and is a blanket term we use to describe anything we don’t want on our recording. It could simply be some background environmental noise that adds context to a location recording but is too dominant and distracts from the subject. Alternatively, it could be electronic interference that’s intermittently and unpredictably plaguing our audio. It’s any background audio that’s surplus to requirements. We want it gone.

Inevitably, the best way to avoid noise is make sure it’s not there in the first place: make sure you’ve got a good microphone and recording equipment, to start with. But even with the best setup, avoiding noise can be easier said than done. Reducing it at the source is certainly achievable and we have plenty of tips to help you with that. 

We also have ideas for techniques to help you fix things in post production. Of course there will be times when your audio track seems to be completely unsalvageable and it makes more sense to replace it. 

But before you throw in the towel, check out our ERA 4 Bundle Pro, which is packed with processors to help clean up noise and reverb, and to improve the sound of spoken audio. 

Different Types of Noise and how to Deal with them

1. Wind

What is it?

Weather conditions can play havoc with your location audio and none more so than wind. As the wind interacts with your microphone diaphragm it generates extra low frequencies. At its worst, this sounds like a nasty noisy rumble, and can dominate the sound. 

Best practice is to keep the wind away from the mic capsule, either by keeping the mic in a sheltered position or by pointing it away from the wind. You should also fit a windshield. Basic foam designs are often included with a mic and work well for light winds. For strong winds seek out a furry design.

Here’s an example of wind noise before and after using a windshield…

Wind noise before and after using a windshield

How to fix it

The additional low frequencies that are created can be filtered out using a high-pass filter, but remember this will also filter out any low frequencies you want to hear, so may not be an ideal fix. 

2. Electrical Noise

What is it?

When you think you’ve got everything set up to perfection, to suddenly be plagued by an electrical crackle – or worse still, a signal dropout – is an absolute nightmare. Invariably, these things happen as a result of a dodgy plug or lead, in which case they can be prevented to some degree by checking and maintaining cables, and by cleaning connections. 

Plugging and unplugging connectors or wiggling them a few times when you’re setting up can help clean dirty contacts, and this may also highlight any weaknesses in advance.  

Electrical noise

How to fix it

Fixing bad crackles afterwards is very difficult. However, small electrical clicks and pops can sometimes be cut out or redrawn using an audio editor.  

Don't forget, our ERA 4 Bundle Pro contains the ERA Noise Remover, which can easily remove noise from many audio sources. Try it out with a Free Trial.

3. Interference

What is it?

The air surrounding us plays host to a complex blend of electromagnetic waves. Most of these go unnoticed but typical problem candidates include mobile phones, Wi-Fi and even lighting circuits. To prevent these from infiltrating your precious audio signals, use balanced cabling throughout your recording chain and ensure problem devices are switched off.  

How to fix it

Interference is hard to fix afterwards, but it may be possible to edit out small momentary noises in a DAW. 

4. Ground Loops

What is it?

Unlike airborne interference, ground loop noise is distributed from one device to another via their physical connections. One common type is mains hum which adds a low frequency buzz to the signal. Computer components such as hard drives and screens can also generate annoying scratchy noises that get distributed via common connections. 

To avoid these issues there are a number of options, including balanced audio cables, ground loop isolating cables and ferrite cores for USB or network cables.

Often, ground loops can be caused by multiple pieces of equipment that are connected together being plugged into different power outlets. Each power outlet has its own ground value which acts as a reference for audio equipment; if two outlets have different ground values, the difference between them can easily turn into a buzzing sound.

Quite simply, run any battery supported devices on battery rather than mains power, or try using just one mains power outlet as the electricity source for all devices (assuming they’re able to be plugged into an extension lead.

Ground loops

How to fix it

Hum is usually easy to remove with a high pass filter. Computer interference is harder to remove but also tends to be quiet, so may be less intrusive. NEVER fix ground loop hum by removing the ground connection from your power supply – this risks serious electric shock.

Don’t forget, our ERA 4 Bundle Pro contains the ERA Noise Remover, which can easily remove noise from many audio sources. Try it out with a Free Trial.

5. Rumble

What is it?

Low frequencies in your surroundings can easily get transmitted along physical connections such as stands and even people, and can be captured by the microphone. The key to avoiding this is building some kind of isolation into your rig. This could be via a decent mic stand or by using an isolating ‘cradle style’ mic holder. Your mic may also include an onboard low -ut filter, which offers an electronic solution, although this may also remove the low frequencies you want to record.

How to fix it

Low frequencies can be removed afterwards using a high pass filter or more surgical EQ; just be aware this may influence the low frequencies you want to hear. If you’re looking for recommendations for a new EQ then check out our guides on The 5 Best EQ Plugins for Video Editors.

6. Mechanical Noises

What is it?

Although most video and audio equipment is quiet, it’s very rarely silent. This means if you’re using an onboard or camera-mounted mic, those noises will be captured as well. Other things such as squeaky stands, loose cabling and even operator clothing can also create problems. 

Because these sounds are nearer than your subject audio, they can easily dominate the audio track. The most obvious solution is to not use an onboard mic. Even so, staying on top of things that you can control – such as cables and clothing – is good practice.

Mechanical noise

How to fix it

Removing these sort of noises is very tricky. Maybe embrace them rather than destroying the audio track trying to fix them after.

7. Equipment Self Noise

What is it?

The electronic equipment in your signal path adds noise and although most modern equipment is pretty quiet, but multiple gain stages followed by compression further down the line can boost this noise floor making it obvious. 

To deal with this at source, it’s important to record a strong enough signal level so that the signal to noise ratio is good. If you can, set the microphone preamp gain manually and have input metering then set the gain so that the meters clearly display the signal. Also remember to leave enough headroom for peaks, as digitally overloaded signals can create horrible distortions.  

How to fix it

Both our ERA-D and Noise Remover plugins can help you clean up noisy recordings.

8. Background Noise

What is it?

Background noise is any sound that accompanies your main source sound and coping with it is a process that starts with choosing the right space and making sure it’s suitably prepared. Outdoors this could involve avoiding noise sources such as traffic or birdsong. Indoors it could be choosing a less reverberant space or making sure windows and doors are closed. 

How much background noise you need to cope with will depend on how you are miking something. Close-up techniques such as a clipped on lavalier mic or handheld presenter mic will successfully minimize most low-level background noise. For more distant sources you need to consider the balance between direct sound and background noise.

How to fix it

Our Reverb Remover can help reduce ambience in your audio track. A more aggressive solution is gating, although this can sound very obvious on an exposed audio track.

9. Plosives

What is it?

If you record someone’s voice up close then you will quickly become aware that certain sounds can make the microphone pop. These suitably named ‘plosives’ are mouth sounds that generate a thrust of wind, and this in turn creates an unpleasant thump on your audio track. 

Thankfully, this only occurs when the mic is in close. Backing the mic away a bit can be very effective. Beyond this the best ‘at source’ solution is a pop shield positioned between the mic and the mouth. A foam windshield can also work and is the only really practical option for handheld mics, however it’s less effective than a pop shield. Of course how much the shield gets in the way visually may also be a deciding factor in your available options. 

Here’s an audio example of plosives before and after using a pop filter:

Plosives before and after using a pop filter

How to fix it

Our Plosive Remover plugin provides a one stop solution to this annoying problem. You can also try using an EQ to notch out the offending low frequencies.

10. Sibilance

What is it?

Sibilance is a burst of high frequencies generated by certain letter sounds such as ‘s’ and ‘t’. The amount of sibilance produced varies from person to person, and if you only have a couple of instances then it’s unlikely to be a problem. Even so, if you later compress or boost high frequencies in your audio track, sibilance will become more obvious and more annoying. 

Preventing sibilance at source can be tricky. Nevertheless, choosing a mic that is less bright, turning the mic capsule off axis or simply backing away from the mic all work. Some foam windshields can also reduce high frequencies and this may also help.   

How to fix it

Try Accusonus’ own De-Esser plug in. It’s easy to use and includes various types of processing so you can tailor it to the task.

March 13, 2020
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