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What is Audio Compression

If you ask a seasoned Music Producer, “What is Audio Compression”, they will tell you that Audio compression is one of the most important and widely used tools they have used while working in the industry.

Audio Compression allows engineers and producers to control many aspects of the audio signal, which we will discuss in today’s blog. Right from knowing what audio compression is to how it works, the best techniques, and what mistakes one should avoid while using this technique. So, let us get into it quickly!

What Is Audio Compression

Putting it simply, Audio compression is a process used to reduce an audio signal's dynamic range. And what is dynamic range? The difference between the loudest and softest parts of the same audio track. As there are multiple elements and several musical instruments used in a particular track, the dynamic range of it can be quite high, with some instruments or elements being much louder than others.

Audio Compression reduces the volume of the loudest parts of the track while increasing the volume of the softer parts so that their volume levels are closer and more balanced. This creates a sound that is now more even and consistent, as there will be fewer drastic changes in volume.

How Does Audio Compression Work

An Audio Compressor analyzes the level of an incoming audio signal that it is fed and then adjusts the volume levels as per the compression settings entered by the user. The whole process is done in real-time.

There are several parameters that a music producer needs to take care of when setting up a compressor to get the desired output. This section has mentioned what all audio compression settings mean and how to use them.

Threshold

Simply put, the threshold level is the pre-set level by the user, determining when the compressor will start compressing the incoming audio signal.

As soon as the incoming signal crosses the threshold level, the compressor will begin to compress the audio.

Ratio

Compression Ratio is another critical parameter for audio compression as it decides how much compression is to be applied to the signal once it exceeds the threshold.

For example, a ratio of 4:1 will mean that for every 4 dB of signal above the threshold levels, the compressor will compress the signal by 1 dB.

Attack Time

Attack Time will tell the compressor how quickly it has to start engaging the signal and compress it after it has exceeded the threshold level.

A fast attack time will result in a more aggressive and noticeable reduction in volume, and on the other hand, a slower attack time will result in an output signal with a more subtle reduction.

Release Time

Release Time is the compression setting that decides how quickly the compressor stops reducing the volume after the audio signal drops below the set threshold levels.

A fast release time will allow the compression to return to normal levels quicker than a slower release time, resulting in a more gradual return to normal track levels.

Knee

The knee is one of the most underrated audio compression parameters. If explained simply, the knee determines how abruptly the compressor starts to compress a signal after it exceeds the threshold level.

A "hard knee" means that the compressor will reduce the gain once the signal crosses the threshold level. On the other hand, a "soft knee" means that the compressor will gradually reduce the gain as the signal approaches the threshold level.

Common Uses of Audio Compression

While the sky is the limit regarding audio compression, we mention some of the most common uses of audio compression that are popular in music production.

Dynamic Control

Dynamic Control is the most obvious mention in this list, as audio compression is mainly used to control the dynamic range of any track. Audio Compression is extremely important for instruments that produce sounds with a wide dynamic range, such as vocals or kick drums. If you’re having trouble choosing a vocal compressor, we’ve prepared a big enough list that fits everyone.

Maintaining the dynamic range of a track helps create an even and consistent sound that gives any track the required polishing touch.

Levelling

Levelling of any audio signal is a very important part of the music production process as it will help control the overall volume of the track, allowing users to prevent clipping or distortion of any form.

Levelling is especially important when working with digital audio, where levels that are too high or low can cause unwanted digital distortion or clipping, or with instruments that are difficult to balance, such as bass or percussion.

Adding Sustain

Audio Compression techniques help in adding sustain to an audio signal simply by reducing the level of the initial transient of the signal and allowing the sustain or decay of the sound to be heard more clearly.

In the case of instruments such as a guitar, adding sustain can reduce the level of the initial pick attack and allow the sustain of the note to be heard more clearly, which makes the guitar sound smoother, cohesive, and more controlled.

Emphasizing Transients

Audio Compression helps emphasize transients of the track to a certain extent if the compressor is set to a fast attack which allows the transient to pass through quickly without getting affected, and with a slower attack time, the sustain levels can be improved, which creates the feeling of a punchy sound. This allows a music producer to make transients more prominent in relation to the rest of the sound.

Creating Character

While it is not generally recommended, users can create unique and interesting sounds with the help of audio compression by pushing certain compression parameters to the extreme ends, such as high ratios or fast attack times.

Most Popular Audio Compression Methods

In the entire history of music production, several audio compression methods have come and gone. This section will discuss some of the most common audio compression techniques currently widely used.

Optical Compression

Since its inception in the early 1990s, the Optical Compression technique has remained one of the most common methods in the field.

An Optical Compressor uses a photoresistor that controls the gain reduction of the incoming audio signal. With the increase in the input signal, the photoresistor becomes more opaque, reducing the amount of light passing through it and causing the gain reduction to kick in.

This process is known for its smooth compression, essential for instrument compressions like bass and kick drums.

VCA Compression

Voltage-controlled Amplifier Compressors, commonly known as VCA Compressor, is one of the latest techniques in the list. As the name suggests, VCA Compression uses an electronic amplifier to control the gain reduction.

Compared to an optical compressor, VCA compressors are more precise and often used on instruments like guitars, pianos, and synths.

Field Effect Transistor Compression

This method, commonly known as FET compression, uses a transistor to control the gain reduction. The technique is quite similar to that of a VCA Compressor. The only difference here is that FET Compressors produce sounds with slightly different tonal characters, which makes them great for working with kick drums, bass, and other percussive instruments.

Tube Compression

Although Tube Compression is one of the oldest methods of Audio Compression, they are still popular in use. Tube Compressors use vacuum tubes to control the gain reduction.

Many music producers still use this method to add warmth and richness to the compressed sound. Tube Compression is great for vocals and acoustic instruments like an acoustic guitar, basically anything that needs extra warmth and character to enhance the music.

Digital Compression

As you must have thought, Digital Compression is the latest compression method in the list. Digital compressors use algorithms to analyze the incoming signal and apply the appropriate amount of gain reduction, which gives it an extremely precise nature.

Their ease of use has made Digital Compression an industry standard for sound engineering and music production across the globe.

How to Master Audio Compression

Although Audio Compression might look easy, there are things you need to understand if you want to master the art of Audio Compression, which can be daunting if you don’t know what you are doing.

Understand the Basics of Compression

The first thing that any rookie should do is learn and understand the basics of compression. Audio Compression is a technical aspect of music production, and relying on half-baked knowledge will do more harm than good.

We have explained all the main parameters of Audio Compression in the above sections, which one should understand to enhance the taste of their music and the mix.

Use Compression for a Purpose

After learning how to compress an audio signal, many technicians start doing it for the sake of doing it as they have made Compression a part of their routine, which should not be the case.

One should only compress an audio signal if they have a clear idea. For example, if they want to add warmth and character to a vocal track or to tighten up the kick drum. Knowing what you want to achieve is extremely important in the process.

Experiment with Different Settings

Producing Music is an extremely creative process that needs a lot of patience; more than anything, one should not be afraid to experiment. While there are rules on how to use compression, you should understand that these rules are only there to guide you and not bound you to certainty.

Don't be afraid to experiment with different compressor settings and techniques. You must understand that every mix will be different, and there's no one-size-fits-all approach to mastering compression.

Things to Avoid in Audio Compression

One should avoid certain things in Audio Compression so you do not negatively affect the mix. Below, we have mentioned some of the most common mistakes you should avoid.

Over-Compression

Over-compression is easily the most common mistake a music producer can make when it comes to Audio Compression, which will result in a flat and lifeless sound, which is a nightmare for any technician.

You should keep reminding yourself that Audio Compression is a tool to control the dynamic range, not something to kill it completely. Use it subtly to keep the natural dynamics of the instrument intact so that it sounds pleasant to the audience’s ears.

Using Compression on Every Track

Another mistake rookies often make with compression is using Audio Compression on every track possible in the mix. Although Compression naturally helps create balance and harmony, making the mix more cohesive, you should understand that it should not be used blindly and is important to use it strategically and sparingly.

Not Listening to the Mix as a Whole

We can not state the importance of considering the mix as a whole while compressing enough. It is the most important thing when applying audio compression to any of your instruments. When compressing a specific instrument, it's essential to ensure that the compression is not causing any unwanted changes in the overall balance of the mix.

Therefore, it is important to pay attention to the interaction between the compressed instrument and the other elements to create a final mix that sounds smooth and cohesive. It should serve all the instruments and vocals instead of focusing on an individual element.

Conclusion

By far, we have learned that Audio compression is undoubtedly an essential tool in music production as it allows technicians to control the dynamic range of a track and create a more consistent and balanced sound.

We have also gone through What audio compression is, the basic parameters of the technique, how you can master the methods of Audio Compression, and the most common mistake one makes while doing it. We have given you a strong foundation you can rely on, but the rest of the journey is your course. The most important thing is to be not afraid of making mistakes. Instead, learn from them!

- Joseph SARDIN - Founder of BigSoundBank.com - About - Contact

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