Compression, Sidechaining, Limiting, and Equalization

When you hear music performed live, there’s variation in the volume. Some sounds are loud, some are quiet. Some may be muffled, distorted, shrill, or filled with echo, but you probably won’t notice when you’re enraptured by the performance visuals. If you were to record the performance live on your phone and play it back later, you’d notice that the sound quality of the recording is poor. There’s background noise, the lyrics are hard to make out clearly, and the bass sound likely overpowers the higher instrument sounds.

When you prepare a song for production, you want to achieve the highest-quality sound you can get. You want the audio to be as clear as possible and emphasize the best parts of your sounds and reduce the unpleasant parts.

Mixing is the name of the process we use to polish our sounds. It includes combining and grouping recordings of instruments in a tool called the mixer...

Understanding compression

When mixing, we call the range in volume from loud to quiet the dynamic range. Compression is an effect to be applied to a sound to reduce the dynamic range. After compression is applied to a sound, the loudest parts of the sound become quieter relative to the quieter parts. The volume of the whole sound is then raised. Reducing the dynamic range means that you have less change between the quietest and the loudest parts of your sound.

Why would you want to use compression? Imagine you were having a conversation with someone and wanted someone else to hear a recording of the dialog. In the recording, some parts of the dialog might be really loud while others might be quiet. You might whisper in some parts and yell in others; you might move close to or further away from the microphone. All of these factors will affect the volume of the end result of the recording. For someone listening to the recording, you don’t want them to be struggling to hear...

Applying gates and expanders

To the right of the ENVELOPE section in Fruity Limiter, we can see the NOISE GATE section:

Figure 6.6 – Noise Gate

Gates and expanders are useful tools for music producers and can be used in a wide variety of situations. They can be used independently from the rest of the controls in Fruity Limiter.

To understand gating, let’s compare it to simple compression. Simple compression works by reducing the loudest parts of a sound above a threshold level. Gates and expanders do the opposite. Expanders reduce the parts of a sound below a threshold level. Gates completely remove the audio below the threshold (don’t allow anything through the gate). Expanders reduce the audio below the threshold but don’t eliminate it completely. From here on in, we will refer to examples using gates, but the same overall concept is used with expanders too.

Why would you want to use a gate? Imagine you had a dialog recording in a...

Applying sidechaining

Sidechaining (also known as ducking) is a compression technique where you use the input of one sound source to determine when to compress a second sound. This technique is used extensively in pop and electronic dance music to sidechain bass instruments whenever a kick drum sound occurs. The result is a rhythmic pumping bass sound associated with the urge to tap your feet and bob your head.

Sidechaining in electronic dance music uses the following rationale: sidechaining the bass sound reduces the bass sound when the kick drum comes in. This frees up space to allow the kick sound transient to punch through and focuses your ears’ attention more on the kick.

It should be noted that sidechaining can be applied to any sound and doesn’t have to involve percussion at all. A sidechain pumping sound of an instrument can be used on its own. For example, you may want to sidechain the bass instrument, even if you don’t have any percussion playing...

Using limiters

So far, we’ve discussed simple compression, parallel compression, and sidechain compression. Fruity Limiter offers another tool, called a limiter. Limiters are tools used to lower the amplitude peak of a sound. Limiters have a threshold level, and when it’s reached, the average volume of the audio is compressed and then raised until it reaches the threshold. The result is that the overall sounds appear louder but are contained under the threshold.

The difference between a compressor and a limiter is that in a compressor, you set the compression ratio to an exact value (for example, reduce by a 3:1 ratio), whereas in a limiter, the ratio is not specifically set by you. The ratio of compression adapts until the overall volume is raised up to the threshold.

Why would you use limiters? One reason to use limiters is to prevent unwanted distortion. If the volume of your final audio exceeds 0 dB, unwanted distortion occurs. In hardware, this causes a...

Applying equalization

In Chapter 5, Sound Design and Audio Envelopes, we learned that frequencies are related to the pitches we hear. By increasing the frequency, we increase the pitch of a sound.

Equalization (shortened to EQ) is a category of filter effect used to increase or decrease targeted frequencies of a sound. EQ is used to enhance the frequencies of sounds you like and reduce those unwanted ones you don’t.

One way that EQ can be used is to clean up muddy mixes. When multiple instruments are playing, instruments may sound like they’re trying to play over one another. The overlapping of sounds makes it difficult to hear any of the competing instruments clearly. This is known as mud in the mix and is undesirable. EQ can help fix muddy mixes by removing competing frequencies of instruments playing at the same time. This helps to designate an area of frequency space for each instrument so that you can hear each one clearly. This is known as cleaning up the...

Summary

In this chapter, we learned about the various types of compressors and equalizers. Compressors can make your sounds appear thicker and fuller. Gates can reduce unwanted background noises. Sidechaining can be used to give your bassline a pumping groove. Limiters can be used to raise the volume of your mix. Equalizers can be used to enhance desired frequencies and reduce unwanted ones.

In the next chapter, we will investigate additional mixing techniques with stereo width.