Broadcast Loudness

Controlling Broadcast Loudness

Loudness-level inconsistencies rank among the most pervasive problems in the broadcast industry. As these inconsistencies can arise from various processes in the broadcast chain, Dolby offers a range of solutions. Our tools include:

Broadcast metadata 

Measurement, analysis, and correction

Consumer-end volume leveling

See the Solutions tab for information on these approaches. 

Download our broadcast loudness brochure for complete details.

Loudness Control

What has long been a commercial issue has become a regulatory one: Worldwide, governments and standards organizations increasingly mandate loudness control. In the US, for example, the Commercial Advertisement Loudness Mitigation (CALM) Act takes full effect at the end of 2012.

Causes of Loudness Inconsistencies

Loudness problems can arise during content creation and at nearly any other point in the broadcast chain. These problems occur for many reasons, including:

Programs come from a wide variety of sources, often created for different replay environments or mixed in different parts of the world.

Content creators may be unfamiliar with setting loudness levels.

Traditional PPM and VU meters are not designed to measure loudness.

Operators interpret traditional meter readings differently.

Signal measurement and loudness have only limited correlation.

Consequences of Loudness Inconsistencies

Poor loudness control can have significant consequences. These include:

A degraded viewer experience

Viewer complaints

Viewers defecting to other channels or providers

Regulatory issues

Loudness Solutions

Because unwanted loudness variations have no single cause, Dolby® offers a range of solutions. These fall into three categories:

Broadcast metadata

Measurement, analysis, and correction

Consumer-end volume leveling

See the Tools tab for specific Dolby hardware and software tools.

Broadcast Metadata

All of Dolby's broadcast audio formats—Dolby Digital Plus, Dolby Digital, and Dolby’s implementation of HE AAC—include full Dolby metadata.

Dolby metadata includes tools that control loudness levels and tailor the audio to the consumer’s replay environment. This metadata:

Gives broadcasters and operators control over final replay

Provides end users with consistent loudness

Can be set in transmission

Employs presets to suit the content genre and station style

Includes listener-adjustable dynamic range modes

Measurement, Analysis, and Correction

Effective loudness control requires accurate measurement. Dolby and our partners offer a variety of effective tools that support a range of international standards, including:

ITU-R BS.1770


EBU R128

The Importance of Dialogue in Measurement

Viewers judge loudness by the level of the anchor element, typically dialogue, in the mix. ATSC A/85 and some other international specifications now explicitly call for loudness measurement using dialogue.

Dolby meets this need with Dialogue Intelligence™, an automatic, consistent technology for accurate dialogue measurement. Available in tools from Dolby as well as from partner manufacturers, Dialogue Intelligence:

Measures signal loudness only during presence of speech

Couples with ITU-R BS.1770 and other standards

Objectively quantifies what listeners subjectively hear

Uses a unique algorithm developed by Dolby's audio experts

Manufacturers who wish to include Dolby technologies in their loudness measurement products can download Dolby's speech-gating reference code free of cost.

Download Now

Consumer-End Volume Leveling

Even with proper use of metadata and control procedures, some programs will still reach the consumer without any loudness control or correction. Other inputs to the TV or set-top box (STB) may come from non-broadcast sources such as Internet-connected devices or user-generated content.

To help resolve this need for volume leveling in programs that lack proper metadata, Dolby created Dolby Volume. Designed for inclusion in TVs, A/V receivers, and STBs, Dolby Volume:

Draws on four decades of research in human sound perception

Offers a new and uniquely effective approach

Delivers natural, artifact-free sound

Preserves audio detail even at very low volume levels

Learn more about Dolby Volume.

Tools for Loudness Measurement, Analysis, and Correction

Dolby offers both hardware and software tools for loudness control.


Dolby LM100 Broadcast Loudness Meter 

The Dolby LM100 Broadcast Loudness Meter accurately measures program loudness using Dialogue Intelligence. The LM100:

Presents results in an easy-to-read numerical format

Incorporates extensive logging functions to help track and pinpoint problems

Learn more about the Dolby LM100.

Dolby Media Meter

Dolby Media Meter, our software loudness meter, also employs Dialogue Intelligence. The Dolby Media Meter is available:

For both Mac® and Windows® platforms

As a stand-alone program or a plug-in for popular DAWs

Learn more about Dolby Media Meter.

Dolby Media Emulator

The Dolby Media Emulator software simplifies the creation of soundtracks to meet existing metadata delivery specifications or to author program-specific metadata. It includes the following features:

Integrates into popular audio workstations

Enables content creators to ensure that delivery specifications are met

Allows monitoring for different consumer replay environments

Learn more about Dolby Media Emulator.

Dolby DP568 Professional Reference Decoder

The Dolby DP568 helps broadcasters ensure that viewers at home will enjoy the highest quality audio. It includes:

Monitoring capabilities for emulating STB behavior in the QC environment

Loudness measurement and logging features

Learn more about the Dolby DP568.

Dolby DP600 Program Optimizer

The Dolby DP600 provides a file-based workflow solution for loudness correction, audio conversion, and upmixing. It has multiple, flexible capabilities:

Expands on Dolby's Dialogue Intelligence technology

Analyzes the loudness of file-based audio encoded with Dolby technologies

Works with content not coded with Dolby technologies

Learn more about the Dolby DP600.

Choose from the drop-down menus below to get Dolby professional reference material.