Besides EQ, compression might be the most ubiquitous term in the audio world. However, it definitely isn’t the easiest to learn. For video editors who handle voice-overs, production audio, or even rough mixing, knowing how to use a compressor will come in handy all the time.


What Is Compression?

To understand compression, you first have to understand dynamic range. In audio, the dynamic range measures the difference between the loudest part of a piece of audio and the lowest. These extreme peaks and valleys, or dynamics, are represented visually by the waveform.

 

audio wave

 

Dynamic range should be taken into consideration when determining where the video or film will end up being viewed. A feature film intended for theaters with superior audio playback should have a very wide dynamic range. Audiences will be able to hear the quiet whispers and be accepting of extremely loud parts. Contrarily, a video meant for the web or social media will probably be played back on laptop or phone speakers. This means a more even and steady mix will probably be the best choice.

 

person sitting in an empty cinema

 

An audio compressor works by smushing, or compressing, the peaks and valleys closer together. With compression, the soft parts get louder while the loud parts get softer at a configurable ratio and speed.

When Should A Compressor Be Used?

Compressing audio has numerous use cases in post-production. While audio engineers are usually compressing a singer’s vocals, video editors commonly use a compressor on voice-overs and dialogue.

Compressing raw voice-overs helps even out the entirety of the audio clip by raising up the softer words and lowering the louder words. The human voice naturally has different inflection points and variances in volume across sentences, which is perfectly normal. However, decreasing the dynamic range on a voice can make it smoother and more balanced. This helps achieve a more professional sounding mix in commercials, interviews, and other forms of video.


Compression Within Premiere

Premiere comes with a few different compressors and presets built in. To apply a compressor (or any other effect) to an entire audio track at once, refer to our post on using the Audio Track Mixer in Premiere.

 

 

Each compressor here is designed for a specific use. Take some time to explore the different compressors to see how each one affects a piece of audio.

For example, the DeEsser focuses on the sharp “Ess” frequencies (sibilance) in human speech and compresses those in order to make the vocal smoother and less harsh.

A popular compressor in Premiere is found in the Dynamics effect, which has the capability to apply multiple effects all within itself.

 

audio compression

 

The image above shows all of the compressor controls within the Dynamics effect. These controls are standard across all compressors in any plugin, program, or operating system, so they are worth learning.



Compression Settings

Threshold: the dB level where the compressor will start working

Ratio: the level of compression it will apply (the higher the ratio, the more compression)

Attack: how fast the compressor will start working when the threshold is reached

Release: how slowly the compressor stops working when the threshold is no longer met

MakeUp: overall gain adjustment control

Most compressors in Premiere and other programs come with built-in presets. Feel free to cycle between compressors and look at the presets if you are in search of a certain effect or sound.

 

The Multiband Compressor

One of the most powerful compressors is the Multiband Compressor. The Multiband Compressor works by splitting up the audio frequencies into different sections, or bands, and then applying compression to each of those bands independently. This allows you to compress the bass, mids, and treble differently to achieve different cohesive effects.

 

multiband compressor

 

The Multiband Compressor is great to use on the master track because it is able to compress the different EQ bands independently. If you had, for example, a bass-heavy music track and a voice-over that was in the mids, you could apply a higher ratio of compression to the bass frequencies in order to make a more balanced mix with the vocals.

Cycle through the presets to find good starting points such as Enhance Highs / Lows, Internet Delivery, and Raise Vocals.

Depending on the compression settings, the volume of the affected audio can be made softer or louder. The Output Gain setting allows you to make a gain adjustment after the compression is applied, much like the MakeUp dial in the Dynamics effect.

Lastly, it usually a good idea to enable the Brickwall Limiter checkbox. A limiter is a type of compressor that is designed specifically to prevent audio levels from exceeding a certain value. As dB levels reach the limit, which in our case is 0 dB, the limiter will apply more and more compression to prevent the audio from peaking and distorting.

 

Wrapping it up

There are many more compressors in Premiere to explore, and a ton is available as third-party plugins. Don’t get too bogged down by the seemingly infinite options of how to compress audio. Instead, pick a compressor in Premiere and use the presets to see how they affect your audio. Cycle through the options until you find something that is close to what you are looking for. Then begin to adjust the different settings to fine-tune the effect.

 

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AUTHOR
Jason Brandel, Filmmaker/Video Editor

Jason is currently offering the Soundsnap community a 95% discount on his top-rated online course, The Complete Audio Guide for Video Editors, which includes 4.5 hours of in-depth video tutorials. Clicking the link automatically applies your discount.