How to Fix Distorted Audio: What Causes Clipping and How to Restore Clipped Audio Files

Anyone who works with sound or in music production with audio editing software knows how frustrating it is to find distorted audio after a long day of tracking.

Whether you are working on the latest hit, producing a podcast, or a video editor putting together a new project, distorted audio can strike anywhere.

Technically, distortion is the change of the original audio signal to something undesired. When a sound is distorted, there's a change in the shape or waveform of the sound.

Distortion is tricky. Once an audio file is distorted, you can't just yank the distorted sound out.

You can do things to soften the blow, but once the signal is distorted, parts of the audio waveform are lost, never to be recovered.

Distortion occurs when you start to notice the sound is glitching and losing quality. It can occur at almost any point in the audio pathway, from the microphone to the speaker.

The first step is to find out where exactly the distortion is coming from.

The problem may be from simple human errors, such as improper level settings, misaligning microphones, loud sounds during recording, and more. Even if you keep your setup relatively error-free, noise, RF interference, rumbles, and faulty equipment can cause distorted audio.

Making audio sound immaculate after distortion isn’t easy. It’s like repairing a broken mug. You can see how distorted audio caused the cracks. You can try to put the pieces together again, but you're not getting an unbroken mug.

Even after repair, subtle sound problems with distorted audio may linger. So, even the best software or techniques risk creating an artifact.

An artifact is sonic material that is accidental or unwanted, caused by the overzealous editing or manipulation of a sound.

But don't worry, with time, patience, and careful listening, it is possible to fix distorted audio to a fairly satisfactory level.

In this article, we'll discuss the common forms of distortion and how to fix them when you encounter them with audio editing.

Clipping

In most cases, clipping is the source of distortion in an audio file. It can be identified by a flattened or clipped-off waveform. While this smushed waveform is easy to spot, you'll probably hear the damaged audio first.

Audio clipping occurs when you push the loudness of your audio signal past the threshold your system can handle. It’s called "clipping" because your system actually “clips” off the top of the waveform after reaching the limit. This is what causes distortion.

It is caused by overload and does not have one specific sound. It can sound like a skip, an empty gap in your audio, or it can present with completely unintended sounds like hisses, clicks, pops, and other annoying distortions that aren't in the original sound.

Clipping sounds very bad to the trained ear and amateurish to the untrained. It's easily heard. One small clip can make for an unpleasant listening experience.

If it happens in a file meant for public sharing, the bad audio quality may bring your professionalism into question.

Clipping can harm your equipment, too. When there's a signal overload, the components of your equipment go into overdrive and that can cause damage. An overdriven signal will push a speaker or amplifier to produce at a higher output level than it's built to.

How can you tell when your audio file is clipped or clipping? It is usually visible on the level meters.

If it's in the green, you're safe. Yellow means you're entering headroom (headroom is the amount of wiggle space you have before the audio clips). Red means it's starting to clip. 

What Causes Distorted Sound

Clipping can be caused by many things at every step of your tracking process, from the mic all the way to your speakers. 

• Microphone: Recording too close to the mic is the easiest way to cause your audio to clip. Some mics can handle exertion better, however, those tend to be more expensive or not good for tracking vocals. If you're recording with a mic, perhaps it is sending audio that is too hot for the system. The same goes for playing guitar or keyboards.

• Amplifier: When an amplifier goes into overdrive, it creates a signal that demands more power than it can generate. Once it has reached its maximum capacity, the audio begins to clip.

• Speakers: Most speakers can't handle playing audio at the maximum volume for a long time. So when they're pushed beyond that, they're easily overwhelmed and clipping isn't far away.

• Mixer/DAW: Sometimes clipping is the result of very aggressive mixing. If this is a result of aggressive mixing you might be able to go back to the original recording and recover a clean version.

Clipping can occur if you record in the mixer or the DAW (digital audio workstation) with a hot signal, which means above 0dB. You can prevent this by adding a limiter to the channel where you are recording.

Some software offers you volume levels up to 200% or more, but you should set any software levels to 100% or lower.

If you need more volume, then you should turn up the volume on your speakers or headphones instead.

How to Fix A Clipping Audio File

In the past, the only solution to fixing a clipped audio file was to re-record the audio that had clipped in the first place. Now we have more options than that. Depending on how badly distorted it is and what the end purpose of your audio files is, you may be able to save your sound with these tools.

• Plug-ins

  Plug-ins are the most popular solution to fix clipped audio today. The most advanced plug-ins work by looking at the audio on either side of the clipped section and using that to re-create the damaged audio.

  This method involves selecting the damaged area and specifying how much the level should be reduced.

  Clippers are plug-ins that prevent your audio from going overboard. They do this by smoothing the peaks with soft clipping starting from the threshold as methods of audio enhancements.

  The faster and higher the peaks, the more you need to bring down the threshold to get good sound.

  They're also very light on CPU and RAM, so it's pretty easy to integrate them into your process when fixing audio distortion.

  Popular audio clippers include:

  • CrumplePop ClipRemover
  • CuteStudio Declip
  • Sony Sound Forge Audio Cleaning Lab
  • iZotope Rx3 and Rx7
  • Adobe Audition
  • Nero AG Wave Editor
  • Stereo Tool
  • CEDAR Audio declipper
  • Clip Fix by Audacity

  CrumplePop ClipRemover is an easy way to restore clipped areas of your audio. Simply apply the plugin, select where the clipping is occurring with the main knob (usually that's at the default setting of 0db) and then choose a new output volume. ClipRemover uses AI to help restore the distorted audio, giving you a more pleasant sounding and professional recording.

• Compressor

  

  If the audio distortion is coming from occasional peaking, consider using a compressor. Compressors are software that reduces the dynamic range of the audio, which is the range between the softest and loudest recorded parts.

  This results in a cleaner sound with less clips.  Professional studio engineers use both a compressor and a limiter to be safe.

  To use a compressor, you have to set a threshold level at which the compression is activated. By turning the threshold down, you reduce the chances of getting clipped audio.

  For example, if you set the threshold to -16dB, for example, the signals that go above that level will be compressed. But turn it down too much and the resulting sound will be muffled and squashed.

• Limiter

  

  Limiters allow users to set the peak loudness in a way that your peak loudness does not make your audio clip. With limiters, you can set the peak volume of the whole mix while still increasing the volume of the separate instruments. It puts a preventative stop to peaking by compressing the dynamic range of your output.

  Limiters are used mainly in the mastering as a final effect in the production chain. It enables you to boost the loudness of your recordings without damaging the way it sounds.

  This method is done by capturing the loudest signals in a track and lowering them down to a level that prevents distortion and preserves the overall quality of the mix.

  Avoid saturation plug-ins as much as possible and be careful with using them. Indiscriminate use of saturation tools is a common cause of clipping when it comes to audio distortion.

Noise

Sometimes your sound isn't distorted in the traditional sense of the word and only sounds that way due to the presence of noise. Often clipping leaves behind noise that remains even after the clipping is fixed.

Noise is one of the biggest problems experienced when recording audio and can be present in many ways.

Most of it is likely to be from your environment. Even though you may not hear your fans and air conditioners, background noise from them can easily be picked up in your recording.

Large rooms are usually noisier than smaller ones, and if you're recording outside, subtle wind can add a troublesome hiss to tracks.

Every microphone, preamp, and recorder adds a tiny bit of noise, and low-quality gear makes it worse. This is referred to as the noise floor. Often, this appears as constant noise and competes with the other sounds in recordings.

Noise that is not constant is even more troublesome as attempts at removing them can end up taking the good audio with the bad. It may be a rumble from heavy breathing into the mic or from wind interference.

Sometimes, it's a low hum from a nearby microwave or fluorescent light - even audio interfaces can produce hum sometimes if they are old or poorly maintained.

Other times, it's just a bad audio quality format or outdated drivers. It doesn't matter what the source is, it's annoying and enough to ruin your sound quality.

How to Fix Noise

• Plug-ins

  

  Plug-ins are really easy to use and a great fix for audio distortion and get rid of your issues. For these audio enhancements, you just have to get the sound profile and play a part of the track where there is only that noise. Then, when noise reduction is applied, the highlighted sound is reduced.

  With all de-noising and noise reduction plug-ins, it’s important to be careful. Removing too much can strip the life from recordings and add subtle robotic glitches. A few popular noise removal plug-ins:

  • CrumplePop AudioDenoise
  • Clarity Vx and Vx pro
  • NS1 noise suppressor
  • X Noise
  • WNS noise suppressor

  CrumplePop's AudioDenoise is an excellent way to approach improving your distorted audio and get rid of any problems. The plug-in itself is easy to use - simply select the portion of your audio file that you want to apply the effect to (or select the entire audio), then start the plug-in. It's as easy as that!

  

  The central control knob allows you to adjust the amount of denoise which is being applied to your audio so you can easily fine-tune the results. You can also adjust the low, medium, and high frequencies to ensure everything is exactly the way you want it.

  For the best in audio denoise, CrumplePop really can't be beaten.

• Good Recording Equipment

  

  The quality of your equipment is an important variable in audio production. Low-quality microphones with poor signal-to-noise ratios are a lot more likely to cause distortion, making a clean audio recording impossible.

  This is the same for amplifiers and speakers and other equipment in your production chain. Dynamic microphones are less likely to distort than condenser microphones, so you may want to invest in those.

  Finally, try to always record in 24-bit 44kHz studio-quality or better, and to have your audio drivers updated.

  Make sure you have protection against electric surges and there are no refrigerators or similar around. Shut off all mobile phones, Wi-Fi, and other similar equipment. 

  The more work you put into avoiding problems, the less audio editing you will need to do after your recording.

• Fixing A Distorted Microphone

  

  To fix low and distorted mic voice recording on Windows 10: 

  • Right-click on the Sound icon in the bottom right of your screen on the desktop. 
  • Click on Recording Devices. Right-click on the microphone. 
  • Click on Properties. 
  • Click on the Enhancements tab. 
  • Check the ‘Disable’ box inside the box. 
  • Click ‘OK’.

  Try to listen to your recordings on a different device to ensure the problem is from the microphone. Some microphones come with distortion-reducing foam shields that help reduce the impact of moving air.  

  Any vibration or movement when recording or using a mic will contribute to some distortion, especially with very sensitive microphones. The higher the vibrations or movements, the more the distortions will be.

  Some professional-grade microphones come with internal shock mounts to deal with this, investing in an external shock mount will help provide mechanical isolation and further reduce the chances of distorting your recording. 

  Less distortion at recording means less need to fix distorted audio after it's been recorded.

Final Words

When your sound is distorted, parts of the waveform are lost. The resulting overages can lead to tonal chaos in your audio recordings and it can happen whether you are a professional audio engineer or just setting out on your first project.

You’re bound to experience distortion and other sound woes at some point during your project or career. With time, patience, and a good ear, you can save your audio from getting distorted and fix distorted audio when it accidentally comes up