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What’s Compression all about?

What is compression and how do I drive it?

What is compression all about?

As a voice over artist, you will hear many people talk about “you must apply compression” to your voice production. And yet there is still a very dark pool about that actually means. So we thought we’d write a short note to help explain what Compression actually is.

Compression 101

Although we’re trying to explain what compression is in a block type article, compression is fundamentally something that is best heard by demonstration rather than description. However, you have to start somewhere. So let’s go – compression is a mechanism of reducing the dynamic range of a signal. That description might sound very technically solid, but unless you have a strong audio background, it’s not actually very useful. So let’s describe this better from a voice over perspective.

Compression is technically a dynamic volume control – when your voice gets to a certain level, thereafter the volume gets turned down by a pre-specified amount that’s a product of parameters call “threshold” and “ratio”. There are other parameters you’ll see on compressors called “attack” and “decay” but, although very important, they aren’t fundamental to understanding the core principals of compression.

So, as mentioned above, the idea is that when the volume of your voice reaches a certain level, the volume gets turned down. The effect of this is that your overall voice gets fuller, fatter and richer … but also quieter. Therefore on the compressor plugin, there’s a control called a “make up gain” which will allow you to increase the volume. And this will deliver a fuller, fatter, richer voice at the original volume. But the downside of all of this is that your compressor will make your noise floor louder. So be careful!

Compression Fundamentals

So when you open your compressor plugin, what are you looking for?

1) Compression Threshold. 

This is the level you need to set that your voice has to reach before the compressor kicks on. So if your voice sits below -15dB and your compressor threshold is above this, your compressor will never do anything. But if your threshold is set to -25dB in the same circumstance, and your voice goes above this point, your compressor will activate. It’s all about looking and, most importantly, listening to your levels to get the best out of your compressor.

2) Compression Ratio

This is the parameter that controls the amount of “volume reduction”. Technically, for every dB your voice goes above the “threshold”, the compressor will reduce the volume by a “ratio”. So if, for example, your threshold was set to -20dB, and your ratio was set to 2:1, when your voice rises to -18dB (i.e. 2dB about the threshold), the compressor would only output your voice at -19dB. i.e. by 1dB – half the increase in loudness by the 2:1 ratio. So what the compressor is doing is dynamically reducing the volume as the signal, your voice, goes above a certain level. And your compressor will normally show this as your “gain reduction”.

This all might sound very technical. But in simplistic terms, all the compressor is doing is when your voice gets above a certain level, it turns the volume down by a predefined amount

So from your perspective, what your compressor is doing is just reducing the volume and making your signal quieter. So this is where you need to look at the final step in the process. The Gain Make Up

2) Compression Gain Make-up

The compression Gain Make-up is a control that will allow you to compensate for the reduction in volume. You need to trust your ears with this. As you lower the threshold and increase the ratio, the overall volume of the output of your compressor will will reduce. Therefore you will need to increase the Make-up gain (or Output gain) of the compressor. This will balance your compressor output. You should always bypass the compressor and check to listen to the audio and then re-apply the compressor to hear the difference. Typically, if you have a few dB’s gain reduction, you will hear a fuller, fatter voice without it sounding squashed … which is what happens if your threshold is too low, and your ratio is too high. It’s very easy to over-squash your voice so be careful!

3) What Does Compression Achieve?

Compression is all about controlling the peaks and troughs in your voice delivery. It effectively reduces the dynamic range between your quiet parts and the loud parts. It smooths out the delivery and makes the quiet part louder and the louder parts quieter.

4) So what does this really mean?

On the positives, Compression can make your voice sound fuller and fatter.

On the negative, Compression can squash your voice and eliminate any dynamics that you might normally want to maintain. And it will also make your voice noisier as it makes the quieter parts louder which effectively means raising your noise floor.

5) So why compress?

Compression is a very common tool used in voice production. It’s really something you might want to consider using if you’re auditioning for a job as it will make your voice sound more “radio”. Most production jobs will ask you to send your voice “as recorded”, but auditions are a bit different! However, leave off the compression for the jobs you do – they’ll normally be asking for the “as recorded” audio.

The main concern with compression is that you don’t reduce the dynamics of your voice too much. You really need to trust your ears and it’s too easy to “squash” your voice too much. If you apply too much gain reduction, your audition will get rejected. You need to keep a healthy dynamic range but make your voice sound fuller – trust your ears!

And there are other parameters beyond this article you need to consider. The “Attack”, “Knee” and “Release”. You need to understand both of these too before you truly master compression. To really hear what’s happening when you change the attack setting. And how having too long a release setting affects your VO. It’s all about trusting your ears.

And this is why we offer our Home Studio 121 Sessions. We can really help you get your arms around Compression and make sure you get the best of it for your productions and really make your auditions pop out.

So if this is something you’re interested in, please get in touch. We’re always here to help.

And if all of this seems very advanced, we always have our Home Studio Workshop to help get you get started.

Hope this note helps. And maybe see you back at Showreel HQ if you need any more help.