When it comes to video with any kind of voice-over audio quality may not be everything, but it comes pretty close!
Any lack of quality in your video projects is like an unseen ninja assassin to the attention of your audience.
They don’t exactly know what made them drift off but they certainly will drift off!
Whether it’s a personal project, a YouTube video or a video for any other purpose the clarity and professionalism of your audio can make or break your project.
One of the most crucial tools in achieving quality audio is compression.
In this post I’ll cover what compression is, why it’s vital for voice-overs and how to use it effectively.
By the end you should have a solid understanding of compression techniques to make your voice-overs sound smooth and polished.
Basics of Audio Compression
What is Compression
Audio compression reduces the dynamic range of a recording which is just a fancy way of saying it makes the quiet parts louder and the loud parts quieter.
This balance ensures that all elements of the audio are audible and clear whilst at the same time ensuring the louder parts aren’t too loud resulting in distortion.
For reasons I will cover later this is very important to how your audience experiences your videos.
A secondary yet still vital reason for the use of compression is that all good audio quality for voice-overs or narrations come as the result of what is called a “process chain.”
Simply put this is the series of adjustments made to the original audio to enhance the quality executed in a particular sequence.
Each step in the chain relies on the earlier step or steps to some degree to end up with the desired result.
Many of the later steps like loudness normalization, limiting and others depend on the “evening” effect that compression achieves for them to be effective.
How Compression Affects Voice Recordings
Whether you are dealing with individually recorded voice tracks or tracks that are part of the video as it was captured inconsistent volume can be subtly distracting.
If some parts of the recording are too quiet and others too loud the viewer will struggle to follow along with your video because they will be losing attention to those fluctuations.
Compression evens out those fluctuations resulting in a smoother, more consistent and far less distracting listening experience.
Key Terminology
Whilst there is a variety of compressors or compression plugins available most follow the same pattern of controls and settings for them to do what they do.
For the purposes of this particular article, I am going refer to the popular and free audio editing software Audacity.
It is widely used, accessible to anyone and has great functionality that is more than enough for the average user.
You can download a copy of Audacity by clicking on this link Audacity Free.
The following are the main and most common settings you will come across and in this image you can see what it all looks like.
Threshold
This is the level, shown usually in decibels (dB) at which the compressor starts to work.
Once the audio signal exceeds the level that has been set the compression is then applied to reduce the volume back down towards the Threshold level.
Noise Floor
This is a dB level that is set so that any noise below that level will not be increased with other quieter parts of the audio that you actually do want increased.
Those kinds of noises will generally be coming from background sounds like air conditioners, fans etc.
By setting a Noise Floor you are telling the software that anything below this level to simply ignore.
Ratio
This determines how much compression is applied once the threshold has been exceeded.
For example, a 4:1 ratio means that if the input signal exceeds the threshold by 4 dB, the output will only exceed it by 1 dB.
Attack Time
The speed at which compression is applied after the signal exceeds the threshold.
Faster attack times catch quick peaks, while slower attack times allow more natural transients.
Release Time
The speed at which compression stops after the signal drops below the threshold.
Faster release times allow the compressor to reset quickly, while slower times smooth out the compression.
Make-Up Gain
Used to boost the compressed signal to match the original volume level compensating for any loss in loudness due to the compression.
Those are the main ones and for the average user more than enough to achieve a good compression effect.
Why Compression is Essential for Voice-Overs
Maintaining Consistent Volume Levels
In voiceovers, maintaining a consistent volume level is crucial.
Listeners should not have to adjust their volume constantly so compression helps achieve this by ensuring that all parts of the recording are at a similar volume.
Enhancing Clarity and Intelligibility
Compression makes quiet parts of the recording more audible ensuring that every word is clear.
This is especially important given the fact that the most commonly audiences will be watching your video on a mobile device or on a computer.
Neither of these scenarios present the viewer with a pristine, high-fidelity environment so missing a single word can change the entire meaning of the message.
Preventing Distortion and Clipping
Without compression, loud peaks in your recording can cause distortion or clipping which sounds unprofessional.
Compression tames these peaks preventing them from exceeding the maximum volume limit and causing audio artifacts.
As mentioned earlier later application of other corrections in the processing chain can be adversely affected by distortions and clipping already present and in fact make it worse.
Key Compression Settings for Voice Overs
Unfortunately, there is no “set and forget” or “one size fits all” system you can use for applying compression to a voice-over track.
Variations in the human voice, the expressiveness of the speaker, the equipment being used or the environment in which it is recorded can all add up to an infinite number of ways tracks can be different.
The best way to approach the task is to listen carefully to the track then apply some basics settings to begin with.
Listen again and repeat this process until you have a reasonably compressed track with no obvious peaks showing and an overall evenness in the volume level.
Threshold
Set the threshold just below the loudest parts of your recording. This ensures that only the peaks are compressed, maintaining the natural dynamics of your voice.
You can work this out by playing back the audio and watching the meter at the top of the screen noting the dB value when it hits the peaks.
Ratio
For voice-overs, a ratio between 2:1 and 4:1 is typically ideal. This range provides enough compression to even out the volume without making the audio sound overly processed.
Attack
A fast attack time (around 5-10 milliseconds) works well for voice-overs as it quickly tames any sudden peaks.
However, make sure it’s not too fast, or it might cut off the natural transients of your voice.
Release
A medium release time (around 50-100 milliseconds) allows the compressor to return to its normal state smoothly. This ensures that the compression doesn’t sound too abrupt and maintains a natural flow.
Make-Up Gain
After applying compression you can use make-up gain to bring the overall level of the recording back up to where it was when you began.
This step ensures that your final output matches the original loudness without any peaks however you can also choose not to do this and adjust the overall volume using Loudness Normalization.
Personally this is how I do it with good results.
Example of Voice-Over Compression
As you can see in the images below, I have a voice-over track that has some high peaks and I know that when I Normalize the audio for YouTube those peaks will exceed the allowable volume.
They will absolutely start clipping and as a result cause distortion.
In this next image you can see that by applying a little compression at a threshold of around 18dB, those peaks have gone and it will now normalize properly.
I haven’t gone beyond that threshold otherwise the voice will become over-compressed and sound dull and monotonous.
So that the balance you are trying to achieve by taming the peaks but keeping as much dynamic range as you can.
Common Compression Mistakes and How to Avoid Them
Over-Compression and Its Effects
- Over-compression can make your voice-over sound flat and lifeless.
- Avoid using too high a ratio or setting the threshold too low.
- Aim for subtle compression that enhances the natural dynamics of your voice.
- Ignoring the Natural Dynamics of the Voice
- Your voice has natural peaks and valleys that give it character.
- Compression should enhance these dynamics, not eliminate them.
- Be mindful of how compression affects the natural flow of your recording.
- Relying Too Heavily on Presets
- Presets can be a great starting point, but they often need to be customized to fit your specific recording.
- Always adjust the settings based on your voice and the context of your project.
Practical Tips from Industry Professionals
Insights and Tips from Experienced Voice-Over Artists
Professional voice-over artists often have unique insights into using compression effectively so here are a few tips:
- Less is more: Subtle compression is often more effective than heavy-handed settings.
- Listen critically: Always listen to your recordings on different devices to ensure consistent quality.
- Experiment: Don’t be afraid to try different settings and techniques to find what works best for your voice.
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