Everything about LUFS: Loudness Metering Explained

everything about LUFS

In this article we’ll go over everything about LUFS.

LUFS are the latest way to measure loudness in your audio.

This new measurement scale is an important development for many issues in music production.

However, understanding LUFS can be pretty difficult at first. They’re different from the ways you’re probably used to measuring your signals.

Even so, these new units are being used all over the audio world. It’s important to know how they work to understand the role of loudness in audio production.

What are LUFS?

LUFS – Loudness Units relative to Full Scale. It’s a standardized measurement of loudness in audio that factors human perception and electrical signal intensity together. LUFS are used to set targets for audio normalization in broadcast systems for cinema, TV, radio and music streaming.

In case it’s complicated, it just means that LUFS are the latest and most precise way to measure loudness in audio.

As simple as it seems, everyone who creates music should know some important consequences of using LUFS for loudness.

Why do we use LUFS?

You may not realize it, but most of the audio you hear in your daily life is tightly produced to sound great in the environment where you experience it.

Movies, TV, radio and streaming services all feature audio meticulously designed to work perfectly on each platform.

But how did we get there? Someone had to decide on the audio standards for each different medium in order to make consistent sound possible.

LUFS are one of the latest tools engineers and researchers developed to help us make those decisions.

By integrating the loudness of audio signals and human perception into a single scale, LUFS plays a role as a kind of audio measuring tape.

The units help engineers compare different types of audio and match them to the requirements of their respective listening environments.

Loudness in music production

The biggest obstacle for consistent sound across mediums is loudness.

It seems like an easy problem, but making everything the same volume for every different playback system out there is pretty tough.

For starters, what even is loudness?

In your DAW you might think of the dB levels on your track meters. That’s a good start, but it doesn’t tell the whole story.

This type of loudness is a property of signals. But it might surprise you to learn that it doesn’t translate directly to how we experience loudness.

The reasons why aren’t exactly straightforward. It has to do with the technique used to measure the signal and the structure of our inner ears themselves.

To learn more about how loudness works, check out our overview.

When it comes to music perception and cognition, things get even more murky, but we broke down the basics in our guide to psychoacoustics.

To fix it, engineers developed a way to gauge listeners’ perceived loudness and signal intensity at the same time—LUFS!

How to use LUFS

Metering audio with LUFS is a little different from the other loudness measures you’re used to

First off, there are a few different ways to use it. Here are the most important ones.

Integrated loudness

Imagine you’re mixing a film soundtrack.

There are some extremely loud scenes with explosions and intense music, and others with barely any sound at all as the characters sit in silence. How loud should the mix be overall?

To make a judgement you’d need to take the entire duration of the mix into account. That measurement is called integrated loudness. It’s recorded in LUFS.

Film and TV have strict standards for integrated loudness that are set in LUFS values.

Dynamic range

Dynamics are important in any recorded audio. However, how big should the difference between loud and quiet really be?

LU—or LUFS without the “full scale” part—can help answer that question. LU uses the same perception based units to evaluate how loud something seems to you.

However, when you measure dynamic range in LU it’s no longer relative to full scale. Instead, it tells you the difference between the quietest and loudest sound over time like integrated LUFS.

Many standards organizations publish recommended dynamic range figures for their own audio content.

Short term LUFS

Integrated LUFS tells you about the whole audio file, but you need to take a closer view of individual sections of sound to get the whole picture.

Even if your track hits the overall LUFS target, there still might be some sections that are too loud or too quiet.

Short term LUFS gives you perceived loudness over the last three seconds three seconds of audio.

Momentary LUFS

Momentary LUFS is the shortest period LUFS measurement. It’s the closest in style to the electrical Peak measurement you’d find on your DAW’s dB meter, but it’s not quite the same.

Momentary LUFS is measured across the last 400 ms of audio.

That’s the kind of fine grain level of detail you need to know exactly how loud your material sounds in the moment.

Why do LUFS matter?

At some point in the history of audio engineering, the music industry decided that recordings should be loud.

The idea was that listeners would subconsciously prefer the CD that sounded loudest on their CD player.

The evidence to support the theory was thin, but it set off a boundary-pushing race called “the loudness war.”

Eventually the trend wore out and loudness was reigned in when streaming platforms like Spotify and Apple Music took over.

Those platforms use LUFS to evaluate loudness.

Since LUFS indicates the perceived loudness, engineers are no longer racing toward the physical limit of the medium’s headroom.

Instead they’re aiming for a target that’s much more in tune with how listeners perceive loudness—and it’s not even close to the max!

Understanding this paradigm shift is important for how you work with your mix in its final stages of development.

In most workflows, these issues will come up most during mastering. Modern mastering is a highly technical art form that pushes your volume levels right to the edge—but never over it.

LUFS is the tool that makes it possible. Measuring audio correctly and hitting the right targets is a key part of any mastering process.

But if you don’t have the tools and experience to evaluate loudness this way, you should consider leaving mastering to the experts.

Whether you decide to hire a professional or try AI mastering, good mastering means getting loudness right every time.

Accurate audio metering

LUFS are an important technical standard in audio.

Loudness is a complicated subject, but with the right tools you can understand how it works and how it impacts your sound.

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