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What Is Audio Compression in Music? (Answered)

I often get asked about audio compression and how it works. In this post, I will answer these questions and more about audio compression.

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Audio compression is used at every stage of digital music production, from sound design to final processing. This makes it an important effect to learn and master. It can be used creatively and musically, but if it is used without thought, it can ruin your music. But what is audio compression, and why is it so important?

This article covers everything about audio compression. So if you’re into music or are just curious about music recording, this post is for you!

Image of a girl with a headphone in front of a monitor. Source: kelly sikkema, unsplash
Image of a girl with a headphone in front of a monitor. Source: Kelly Sikkema, Unsplash

What are audio compressors? Audio compressors and limiters are used in the recording and mixing processes to narrow the dynamic range of an audio signal, making it more consistent in volume. In the hands of an expert, they may make for much louder and more polished recordings.

What is audio compression in music?

The compressor is one of the most beneficial effects for creating polished, radio-ready recordings. They can add color and tone to your music and increase your tracks’ volume, punch, and overall balance.

Audio compressors and limiters are used in the recording and mixing procedures to restrict an audio signal’s dynamic range and make it more constant in loudness. As a result, they may produce significantly louder and more professional recordings in the hands of an expert.

You may set your levels so everything sounds good in one spot, but as the song progresses, some things may be hard to hear or get too loud and jump out of the mix. Compression is often used to prevent this and provide a more unified sound.

It’s important to note that excessive compression can kill the energy in a recording. As a result, mastering the fundamentals will guarantee optimal use of this crucial resource.

If you are in the market for a physical audio compressor that can give your music a rich, full tone, check out this tube compressor.

  • Fully discrete signal path Utilizes custom USA made CineMag input and output transformers Utilizes USA made Kenetek opto attenuator Premium Tung-Sol and Electro-Harmonix tubes Variable Pre-emphasis, allows for compression high-pass filtering Stereo-link capability XLR and TRS balanced line level inputs - 600 ohms impedance XLR and TRS balanced line level outputs - 600 ohms impedance Frequency Response +/- 1 dB, 15 Hz to 20kHz Gain 40 dB +/-1dB Input Level +16 dB max
  • True to its inspiration; the WA-2A boasts an all tube, completely discrete signal path with through-hole component topology
  • It also features custom, large-core Cinemag input and output transformers, four premium vacuum tubes, and the legendary Kenetek opto-cell, considered by many to be the world’s finest
  • No plug-in or other compressor type quite compares to the warm, forgiving, fluid qualities of this classic optical tube compressor
  • For decades, the renowned ‘2A type circuit has become the go-to device for seamlessly handling vocals, bass, and a wide variety of other instruments and program material in an effortlessly smooth way

Why is audio compression used?

An audio compressor can reduce the dynamic range of an audio signal, lowering the volume of loud sounds while increasing the volume of quiet ones, which can be useful for everything from an acoustic guitar with excessive pick noise to a piano with a short punch.

Sound engineers use “audio compression” technology to make music and podcasts sound better by removing unwanted noise and making each sound clearer.

It’s uncommon for the loudest parts of a sound to overpower the quieter parts. The sound of a recorded drum set is a useful analogy. The sound that starts quickly when the drumstick hits the skin is a classic example of a transient. This is the word for the sudden increase in volume at the beginning of a sound.

The transient is the most intense part of the signal in almost all types of sound. Generally, transients and sustained sounds need to be compressed so you can hear them both. For example, in drubbing, compression lowers the volume of the deep strokes of the stick while raising the volume of the long-lasting tones and the drum’s decay.

Image of a screen with purpple and green display. Source: pexels, pixabay


How does audio compression work?

A compressor’s main job is to lower the volume of a signal whenever it gets louder than a set threshold. One may adjust the compressor’s settings to tailor its behavior to their needs. Here are some principles of compression and their significance.

Attack time

After the signal has exceeded the threshold, the attack time is the amount of time it takes to be compressed to the desired ratio. This will change the onset of the sound. For example, with a slow attack, you can quickly squeeze the sound of a loud guitar pick, and with a fast attack, you can give a soft instrument, like a keyboard, more punch.

Release time

The release time is known for how long it takes for the audio signal to go from being compressed to uncompressed. Fast-release speeds sound most natural when the gain is reduced slightly. However, the pumping effect, or abrupt loudness spike, that results from high compression with a quick release time may make the recording seem uneven in various musical styles.

Threshold

The onset of compression is referred to as the threshold. Once a threshold is set, audio below that level will continue to be processed normally, while audio above the threshold will be compressed based on the ratio chosen. You would want to configure the compressor, so the threshold gets the loudest recording area.

Ratio

Once a signal crosses the threshold, the ratio tells how much it will be weakened (or compressed). For example, audio volume is measured in decibels (dB); thus, if you choose a 3:1 compression ratio, every 3dB of the input signal over the threshold will yield 1dB of the output signal.

Knee

The knee refers to how rapidly it goes from compressing to decompressing the signal. Since the compression of a soft knee starts gradually, the sound is less abrupt than that of a hard knee. Producer, engineer, and mixing artist Gus Berry says to use a “soft knee” for bass guitar and vocals and a “hard knee” for percussion instruments like the piano and kick drums.

Make-up gain or output gain

Since a compressor actively lowers the volume of parts of the signal, the output signal will be quieter than the signal that went in. So if the signal level has gone down, “make-up gain” can bring it back up. Rodocker suggests playing the music while bypassing and turning on the compressor, then adjusting the make-up gain until the two sounds are about the same.

What are the types of compressors?

The overall influence on the sound is determined by the settings you make and the type of compressor you choose, so below are the audio compressors you can choose from.

Tube compressor

The tube compressor is one of the earliest compression methods employed by the Beatles and Motown. It is best for bass, drums, and vocals. According to Rodocker, the hallmarks of this style include “slower attack and release timings” and a “particular sound that listeners frequently think of as ‘old school’ or antique.”

FET compressor

FET compressors are a type of analog compressor in which a field-effect transistor (FET) serves as the central component of the circuit. These compressors act quickly and preserve transients better than other compressors.

Parallel compressor

A parallel compression method combines a raw or moderately compressed signal with a highly compressed one. When the softest sounds are amplified, the dynamic range is narrowed. The electric bass, vocals, and live sound benefit most from this.

Sidechain compressor

To adjust the intensity of one instrument’s influence, sidechain compression uses the volume of a different instrument as the master control. For example, it is common practice for dance/pop mixes to have the bass compressed more heavily around the time the kick drum is played. This helps the bass maintain its clarity and prominence throughout the song. The bass guitar and kick drums benefit most from this effect in dance pop.

Multiband compressor

A multiband compressor enables you to compress individual frequency bands in a recording. For instance, if a vocal’s bottom end is overly boomy, it may be toned down but left alone. Vocals, acoustic guitars, and percussion sound the best here.

If you want even more tips and insights, watch this video called “What is Audio Compression? How to Use a Compressor | LANDR Mix” from the LANDR YouTube channel.

A video called “What is Audio Compression? How to Use a Compressor | LANDR Mix” from the LANDR YouTube channel.
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Frequently asked questions (FAQ)

Do you still have questions? Below are some of the most commonly asked questions about audio compression.

 Do you need audio compression?

No. The dynamic range of the sounds you deal with will often be limited. Therefore, audio compression isn’t required and may even be counterproductive in some scenarios. Compressor plugins are best kept for audio with greater movement.

How would you know if your compression was done right?

A well-compressed music should sound better without changing the song’s essential musical elements. For example, it should provide a heavier groove when applied to drums. Likewise, it should enhance the performer’s voice when used on vocals.

When should you compress the audio?

Compression is often used for two major purposes: saving energy and reducing movement. Compression makes sense when you want to emphasize a sound’s explosive transients or moderate its dynamics. However, sound compression may be unnecessary if you’re not doing one of these things.

Conclusion

With the help of this post, you should have a solid grounding in audio compression and its typical characteristics. However, just as you can’t become an expert cyclist by reading a book, you can’t become an expert by reading an article. So now it’s time to open your DAW and play with compression yourself.

This article covered audio compression, how it works, and why it is important in the music industry. Here are some key takeaways:

Key takeaways

  • Audio compression is a technology used by sound engineers to improve the quality of recorded music and podcasts.
  • Audio compression can add color and tone to your music and increase your tracks’ volume, punch, and overall balance.
  • The overall influence on the sound is determined by the settings you make and the type of compressor you use.

So, have you tried compressing audio? And did I cover everything you wanted to know? Let me know in the comments section below (I read and reply to every comment). If you found this article helpful, share it with a friend, and check out my full blog for more tips and tricks on music. Thanks for reading, and never stop making music.

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Audio Apartment Author
Written By Andrew Ash
Hey there! My name is Andrew, and I've been making music since I was a kid. I now run this blog all about home studios and music production. If you want to improve your home studio setup, this is the place for you!

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