Introduction to Audio Effects: EQ, Compressor, Reverb, Delay
Introduction to Audio Effects
EQ, Compressor, Reverb, Delay
If we compare it to cooking, our journey so far has been like this. In Part 2, we learned about the properties of ingredients, and in Part 3, we learned how to create those ingredients. This part is about cooking tools.
There are hundreds of effects in the world, but 80% of practical work consists of four: EQ, Compressor, Reverb, Delay. The latter part of this article will cover the prerequisites for using these effects, which directly relates to why we created VARCO Sound in a multi-track manner.
EQ, the Volume Controller for Frequencies
It is a tool that selectively boosts or cuts specific frequency ranges. The Low·Mid·High distinctions from Part 2 become practical knowledge here.
There are three principles:
- Cutting comes first.
It’s more natural to cut out the bothersome parts rather than boosting the good ones. If there’s a rumble, try cutting a bit around 200-400Hz, and if the sound feels nasal, cut a little around 800Hz to 1kHz.
- High-pass is a habit.
For sounds that don’t need low frequencies, clean up the unnecessary lows. This helps prevent muddiness when multiple sounds overlap.
- Cut significantly to find the cause, then apply minimally.
When identifying problem areas, be bold in cutting, but apply only around 3dB in practice.
Compressor, the Automatic Volume Control Robot
It automatically compresses loud sounds to reduce dynamic range. Sounds become tighter and more consistent.
- Threshold: The baseline above which sounds will be compressed.
- Ratio: How much to compress. At 4:1, a sound that exceeds the threshold by 4dB will be compressed to just 1dB over.
- Attack: How quickly compression starts. A slightly slower attack allows the initial transient to come through, adding punch.
- Release: How quickly to stop compressing.
- Makeup Gain: Compensation that raises the overall volume back up to account for the reduction.
When applied to percussive sounds, it tightens them up, and when applied to dialogue, it reduces the difference between quiet and loud voices, making it easier to listen to.
Reverb, Adding Space to Sound
It artificially creates reverberation from reflections off walls and ceilings. When applied to a dry sound, it can instantly transform it into a cave, cathedral, or narrow hallway.
- Size / Decay Time: The size of the space and the length of the reverb.
- Pre-delay: The short gap between the original sound and the first reflection. A longer pre-delay maintains the clarity of the original sound.
- Mix (Dry/Wet): The ratio of the original sound to the reverb. This is often the value that beginners excessively raise. There’s a saying that if the reverb sounds good, it’s already too much.
In games, reverb is used not just for spatial reproduction but also as a tool for depth perception. If there’s a lot of reverb and the high frequencies are dark, it feels like a distant sound; if it’s dry and bright, it feels like a sound right in front of you. It becomes a device that indicates the enemy's position through sound.
Delay, Designing Echoes
It repeats the original sound after a certain time.
- Time: The interval between repetitions.
- Feedback Gain: A parameter that determines how much quieter the sound will be compared to the previous one during repetition.
- Mix: The ratio compared to the original sound.
To Apply Effects, Sounds Must Be Separated
If you’ve read this far, it’s time to touch on an important premise. All the effects described so far come with one condition: the sound you want to manipulate must be separated from other sounds.
Imagine a battle scene in a forest. What if the sounds of wind, footsteps, and clashing swords are combined into one file? If you receive feedback saying, "The footsteps are too loud," there’s nothing you can do. Lowering the volume will also lower the sword sound, and applying EQ will affect the wind sound as well. You would have no choice but to recreate it from scratch.
This has been a long-standing issue in generative AI sound. Most tools output audio that is combined into a single chunk. Even if 80% of the result is satisfactory, if there’s no way to fix the remaining 20%, it cannot be used in practice.
This is why we created VARCO Sound in a multi-track output format. By separating the sound elements that make up a scene into individual tracks, it allows for applying a compressor only to the footsteps track and a high-pass filter only to the wind sound track. You can adjust the volume of specific elements or even replace them with entirely different sounds. The Layering discussed in Part 1 is preserved in the final product.
One thing to note is that even if the tracks are separated, it’s useless if you don’t know what to do. The value of multi-tracks is particularly significant for those who know how to handle the effects learned in this article. This is also why we are writing this series.
Effect Chain, The Order of Application is Also Design
Effects are usually connected in series, and the order can change the results.
Once you get used to it, try intentionally reversing the order. Applying a filter after reverb to darken only the reverb is one of the fun aspects of sound design.
Frequently Asked Questions (FAQ)
Q. Do I need to buy paid plugins?
You don’t need to at first. All DAWs come with basic EQ, Compressor, Reverb, and Delay built-in, which is sufficient for learning the basics.
Q. What’s the difference between EQ and Filter?
A filter is a simple tool that adjusts a single band, while EQ is a comprehensive tool that precisely boosts and cuts multiple bands. You can think of EQ as containing several filters.
Q. How many effects can I apply?
Use the ability to explain why you applied the effects as a criterion. Effects without purpose only muddle the sound.
Try Editing by Track Yourself
When you create a scene in VARCO Sound, it comes out divided into element-specific tracks. By applying EQ and Reverb to individual tracks, you will physically understand the difference between a combined file and separated files.
