Overview: Before and After Loudness Processing

Butterfly Meter - Introduction

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The Butterfly Meter™ displays your content pre and post loudness normalization - and it's an integrated part of the aNorm algorithm.

The innovative 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.




  • See How and Why Your Audio is Processed

    Instant Pre and Post Processing Overview at a Glance.
  • Four Measures. One View. Times Two.

    Pre/Post Sliding Loudness, Program Loudness, LRA & Short-Term Loudness.
  • A Match Made in Heaven

    The Butterfly Meter and The Radar Meter Complement Each Other Perfectly.

How to Read The Butterfly Meter

The color scheme of the Butterfly Meter is similar to our Radar Meter. Yellow represents loudness above the pre-defined target level and the green colors show loudness below the target. You can change the display scale to your preference in the settings. The example below has been set to 6 LUFS/LKFS steps.


The left side of the graph represents your input signal before any loudness processing is applied.

Loudness Range

The square brackets indicate the Loudness Range (LRA). The left bracket indicates the LRA of the signal before processing; the right bracket indicates the LRA after processing.


The right side of the graph shows a loudness histogram post normalization and post processing.

Program Loudness

The blue triangle on the left side indicates the Program Loudness level at any given time.

Program Loudness Target

The blue triangle on the right side shows the Program Loudness of the processed signal. It should 'float' closely around the highlighted 'target line' (in this case -24).

Short-Term Loudness

The bargraph meters display short-term loudness before and after processing. Just right for checking e.g. dialog level.

Pre-Processing Loudness

Loudness histogram of the input signal before processing, subject to the sliding window selected.

Post Processing Loudness

Loudness histogram of the input signal after processing, subject to the sliding window selected.

Time Since Last Reset

Shows the time since your last measurement reset.

A Match Made in Heaven

The Butterfly Meter is not meant as a substitute or a replacement for our legendary Radar Meter. In fact, the two complement each other perfectly as they are created for two very different tasks: the Radar Meter shows loudness history with critical details in a single view and the Butterfly Meter is your processing meter, focusing on loudness pre and post processing.

In the chart below, you can get an overview of the key differences between the Radar Meter and the Butterfly Meter.

Radar-Butterfly Comparison


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.

aNorm - Main

The Butterfly Meter: Part of aNorm

The Butterfly Meter is an integrated part of the aNorm algorithm, which is not just A new norm - it's THE new norm for loudness processing.


Learn More About aNorm

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.


Loudness Authority logo 2016

Loudness Website

Keeping track of the multitude of issues around loudness can be a challenge. That's why we've created a one-stop dedicated loudness website where you'll find critical information on the most important issues.

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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