aNorm: The Loudness Revolution Continues

aNorm Introduction

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aNorm™ Adaptive Loudness Normalization for DB6 and Loudness Pilot is not just A new norm. It's THE new norm for loudness processing.

It's a new adaptive approach to loudness normalization, and it's easier to set up and use than any other loudness correction solution.

At the same time, it delivers stellar audio quality and keeps you safely within the boundaries of international loudness standards and legislation.

aNorm also introduces a whole new way of visualizing pre and post loudness processing: the beautiful Butterfly MeterTM shows you exactly what happens to the program and why.


  • If It Ain't Broke, Don't Fix It

    aNorm Hits the Loudness Target without Squashing Your Audio.
  • Two Main Parameters. One Amazing Result.

    Set Loudness and LRA Targets and You're Good to Go!
  • Butterfly: Next-Generation Metering

    Loudness Processing Meter. Get an Instant Overview of Your Audio Pre & Post Processing.

If It Ain't Broke...


aNorm is a revolution in streaming processing in several ways. It keeps dynamics processing at a minimum by normalizing your signal intelligently first

Only if normalization by itself isn't enough to hit the Loudness and LRA targets, aNorm applies dynamic processing.

Further, aNorm adapts intelligently, using just the right tools if dynamic processing is needed. It will never just apply heavy compressing as default.

In other words, aNorm hits your pre-defined loudness targets without squashing the audio. 

Two Main Parameters


Loudness is a complex field, but aNorm allows production and transmission to be tied transparently together using two basic parameters: Loudness Target and Loudness Range Target.

Before the output, the most discreet and audio-friendly limiter in the pro industry rounds off the program, making it ready for linear delivery (or any type of data reduction required) for a certain platform.

Once production and transmission are aligned with all targets, production criteria can be refined, thereby automatically making aNorm do less, and maybe eventually only smoothen out transitions.

aNorm Loudness Settings

Main Parameter 1: Loudness Target

Simply set the target level for your Program Loudness here. Typically -23 or -24 LUFS/LKFS for HD TV and -16 LUFS/LKFS for mobile platforms.

Main Parameter 2: LRA Target Max

Use this slider to set how high a Loudness Range (LRA) is tolerated. The lower it's set, the more dynamic loudness processing will be applied on top of auto-normalization.

Input Content

Use this setting to tell aNorm if the incoming content has already been normalized. When in doubt, set it to 'Not Norm.'


Use this button to reset the loudness processing at any time. When you click it, a new 'round' of loudness processing begins. Ideally, aNorm should be reset during the transition from one program to the next.

Normalized Level

If your input signal is normalized, use this slider to tell aNorm the already-normalized level.

Butterfly Meter Scale

Use this setting to choose between metering on an 'absolute' or a 'relative' scale.

aNorm Gain Meter

This horizontal meter indicates how much gain (dB) aNorm adds or subtracts during loudness correction.


Indicates upconversion from mono or stereo to 5.1.


Indicates downmix from 5.1 to stereo or mono.


Shows if loudness is being increased or decreased during processing.

aNorm Demo Videos

Butterfly and Radar Horizontal

In these demos you can hear and see how aNorm handles different types of centent, tasks and delivery platforms.

When looking at the Butterfly Meter, please notice that it shows pre and post loudness processing. The pre-processed signal is on the left side and the processed on the right.

Keep an eye on the little blue triangles on either side. They indicate Program Loudness, but bear in mind that most broadcast standards leave a tolerance of +/- 1 LU and that the idea is not to be on-target at all times - it is to hit the target overall, while preserving dynamics and precious audio quality.

At the end of each video, you will see a switch to our Loudness Radar Meter to verify that aNorm hits the target as expected.

To avoid violating copyright laws, no more than a total of 40 seconds are used for each of the demos. 

Pre-Normalized Music

aNorm Demo: Pre-Normalized Music

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If it ain't broke, don't fix it! Dire Straits' Brothers in Arms is from an era where wide dynamics were allowed to exist in music. Therefore, since the target LRA is at 14 LU and it has already been normalized, almost no processing is needed. Had you chosen a smaller LRA, aNorm would start processing dynamics.

First, you hear 20 seconds of the first verse followed by 10 seconds of guitar and finally the last 10 seconds.

At the end, we switch to the Loudness Radar Meter showing the exact measuring result and then back to the Butterfly Meter where you can see the Program Loudness (blue triangle, right side) hitting the target very precisely.

Non-Normalized Speech (Fast Processing)

aNorm Demo: Non-Normalized Speech (fast processing)

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Radio announcement on D-Day, June 6th, 1944. aNorm has been set to do fast normalization of the non-normalized speech.

aNorm does not compress, since the speech is already very precise with small LRA.

In the demo, you hear the first 20 seconds of the announcement, and then the last 20 seconds. 

At the end, we switch to the Loudness Radar Meter showing the exact measuring result and then back to the Butterfly Meter where you can see the Program Loudness (blue triangle, right side) hitting the target very precisely.

Non-Normalized Drama

aNorm Demo: Non-Normalized Drama

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In this example, we use a short clip from Game of Thrones, the 'Wedding' episode. The original program has a wide LRA at 19.5 LU, and the LRA target has been set to 10 LU.

First, you hear 20 seconds of music and ambience, then a switch for 10 seconds of speech and then 10 seconds of fighting.

At the end, we switch to the Loudness Radar Meter showing the exact measuring result and then back to the Butterfly Meter where you can see the Program Loudness (blue triangle, right side) hitting the target very precisely.

On-the-Fly Normalization for Mobile

aNorm Demo: On-The-Fly Normalization for Mobile

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In this demo, you can see and hear on-the-fly normalization and processing of a BBC Radio 4 speech program. It is being converted for Mobile and PodCast simultaneously (Loudness Target at -16 LUFS). Notice the fine and inaudible limiters, which are important when targeting a limited headroom.

First, you hear 20 seconds of male voice, and then 20 seconds of female voice from the same radio show.

At the end, we switch to the Loudness Radar Meter showing the exact measuring result and then back to the Butterfly Meter where you can see the Program Loudness (blue triangle, right side) hitting the target very precisely.


by Rob James

In action the process is surprisingly transparent. I tried it with a variety of material, some quite challenging and I would have been happy to transmit everything I heard. The new Butterfly meter gives an intuitive overview of the audio pre and post loudness normalisation. aNorm running on a DB6 is a well executed answer to a problem that is or will be faced by most broadcasters.

You Also Get...

aNorm processing and the Butterfly Meter are part of the LoudnessWizard II 'combined' algorithm. But on top of revolutionary, adaptive loudness processing and never-before-seen pre/post processing metering, you also get the great tools from the original LoudnessWizard, including state-of-the-art up and downconversion and True-Peak Limiting.  



Automatic, realtime 5.1 upconversion that continuously monitors the format of the incoming audio. If the signal falls back from a true 5.1 to stereo, it seamlessly cross-fades into a convincing 5.1 surround up-conversion without adding any interruptions or artifacts.

Detection does not require metadata or GPIs to function correctly, and the processing delay is only 2.8 ms (less than 1/10th frame). So, you don't need extra delays to maintain A/V sync.


Depending on your delivery platform, you may need to downmix. This takes place at an overload-proof 48 bit resolution. Transparent transcoding keeps the output perfectly conditioned for mobile TV, iPod or IPTV.

You can even transcode a feature film with a wide loudness range automatically on the fly at an impeccable audio quality.

True-Peak Limiting

Normalizing loudness based on 'perceived loudness' can lead to peaks that might overload. To cope with this, True-Peak metering and limiting is your last line of defence.

Your signal gets upsampled so that even inter-sample peaks are detected. The True-Peak limiting aspect of aNorm handles transient peaks seamlessly, keeping your audio at its finest. 

aNorm - Butterfly Meter

Included: The Butterfly Meter

The Butterfly Meter is an integrated part of aNorm, displaying your content's pre and post loudness normalization.

The graph instantly gives you an overview of how and why the incoming audio is adjusted.

In other words, the sheer look of the meter is just as astonishing as it is intuitive and informative.


Learn More About the Butterfly Meter


  • 2nd Generation Loudness Processor

    Built from ground up to hit loudness targets without sacrificing audio quality.
  • Adaptive Normalization. Adaptive Processing.

    aNorm adapts to the program seamlessly in several ways.
  • Independent LRA Setting

    Dynamic processing is automatically invoked if a certain LRA is exceeded.
  • All Programs and Platforms Handled

    Normalized and not-normalized content. HD, SD and Mobile.
  • Sweet Transitions

    Soften program transitions, even for non-normalized content.
  • Program Interruptions Handled

    Break for commercials and resume processing afterwards.
  • Butterfly Meter

    New pre/post loudness meter showing how and why audio is processed.
  • Compliant with All Major Broadcast Standards

    ITU BS.1770-3, ATSC A/85, EBU R128, OP-59, Reg #354,TR-B32 and more.

Loudness Correction: 1st Generation vs 2nd Generation

aNorm represents a giant leap in loudness processing. The way it adapts to the incoming content on several levels is nothing short of a breakthrough in loudness. A path towards hitting loudness targets without an audible penalty has arisen, while also taking a big step closer to a world of smooth transitions between programs of very diverse nature.

1.gen. - 2. gen. Loudness Adjustment
DB6 featured

Available for DB6

aNorm and the Butterfly Meter are available in the optional LoudnessWizard II license for our DB6 Broadcast Audio Processor unit.  

Learn More About DB6

Keeping You Up To Date

We have been listened to by those actively setting broadcast standards - we've even donated our technology to many of the same international bodies that impact your broadcast work.  

Legislation on loudness in television is constantly evolving.  However, regardless of your location and no matter which TC Electronic Loudness units you use, we will always help you remain compliant with the latest revision of the broadcast standard that impacts your work.


To Normalize or Not To Normalize?

2b or not 2b

The goal for any audio-conscious broadcaster is to loudness-normalize programs before transmission. In our published research, we have shown how transparent normalization is the audio-friendly, low cost concept that prevents blurring of foreground and background elements, works across genres, works across platforms and works across codecs - now and in the future.

Only with proper attention to normalization, rather than to extensive transmission or consumer processing, the spirit and the revolutionary improvements from EBU R128, TR-B32, ATSC A/85 etc. can reliably make it through to the listener.

Tell aNorm When to Hold Back
Pre-normalization of all content may not be achievable from the first day of a station's transition to loudness. An important parameter for aNorm is therefore to know whether or not a program has already been normalized. The setting of this parameter should ideally change based on the status of the content, and there are several ways you can make that happen:

  • Metadata in the SDI Stream
  • GPI Switching
  • Control via Ethernet

Regardless, the long-term aim is obvious: move towards file-based pre-normalization where possible, in combination with live broadcast based on loudness meters. With these principles checked, aNorm can be left mostly in Normalized mode, now primarily taking care of excessive true-peak or loudness excursions based on delivery platform. 

Broadcast & Production Sales Team

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Loudness Website

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The site is an answer to the highly relevant question:
"What Is Loudness, and Why Is It Important?"

Visit the Loudness Website


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