As a follow-up on Mike’s Understanding Loudness, which is now free, in this article, we are going to cover loudness for music streaming services, including loudness normalisation, album normalisation and how to prepare music tracks for music streaming services, with three free tutorials.

What Has Gone Before

In Part 1, Why Do We Need Loudness? We clarified what we mean by loudness, investigated how our hearing works, why we have changed our audio metering systems and presented the solution to loudness changes that consumers complain about.

In part 2, The Development Of One Loudness Standard, we covered the development of one loudness standard. We explored how we arrived at a loudness measurement algorithm that works just like our ears and the various criteria we use to define and guide us when working to the new loudness delivery specifications, including K Weighting, the differences between Momentary, Short-term and Integrated loudness as well as the importance of True Peak and Loudness Range.

In part 3, Calibrating Your Monitors, we covered a key part of delivering loudness-compliant content - how to calibrate your monitors.  We looked at how our monitoring should be configured and provided an explanation of bass management and what your sub should be doing before moving on to a practical demonstration of how to calibrate your monitoring with a sound pressure meter.

In part 4, Creating Loudness-Compliant Mixes For Broadcast And Netflix, we covered some tips and tricks for mixing to the broadcast loudness standards for a wide variety of genres. We will include examples and demonstrations as well as explain the importance of what Mike describes as ‘loudness planning’ before ending with some specific tips and tricks for mixing short-form content like adverts, trailers and promos. Before moving on to cover the Netflix delivery spec brought to the world of Loudness.

What About Loudness For Online Content?

To start with, let’s take a look at loudness for all online content.

Ever since we started using -23LUFS or -24LKFS for broadcast content, there has been a consensus that -23/-24 would not be suitable for portable devices because there wasn't enough gain in the headphone amps to deliver an acceptable volume, with content made to -23/-24.

A number of services, including Apple, settled on -16LUFS and we deliver our weekly podcast at -16LUFS too.

In late 2015, the Audio Engineering Society (AES) published Technical Document - AES TD1004.1.15-10 - Recommendation for Loudness of Audio Streaming and Network File Playback in which they recommend a window of -16 to -20LUFS. Looking at the graphic above, many of the key players in streaming have gone outside the AES recommended window, with Amazon, Spotify, TIDAL and YouTube have all gone for -14LUFS.

In 2017, the Loudness Petition Group was set up by Eelco Grimm, Bob Katz, Matt Mayfield and Ian Shepherd with the express aim of bringing peace to the loudness wars. If you want to know more then we explored this in detail in these two articles…

1. Bring Peace To The Loudness Wars - Recommendations For Loudness Normalisation - Part 1

2. Bring Peace To The Loudness Wars - Recommendations For Loudness Normalisation - Part 2

In the first article, we looked at the Loudness FAQ from the Loudness Petition Group, which expands on the issues and covers some of the misconceptions and urban myths that have already grown up around this whole subject.

In the second article, we looked at the research that Eelco Grimm undertook with HKU Muziek en Technologie, University Of The Arts in Utrecht in the Netherlands, in cooperation with the music streaming service TIDAL and presented at the Berlin 142nd AES convention.

More recently, in April 2020 the European Broadcasting Union (EBU) updated their R128 Loudness Standard to include specs for Streaming Services. R128 s2 (Loudness in Streaming) recognises that streamed content - both live programmes and files - has become “an increasingly important distribution method for EBU members”.

It points out that conventional broadcasters are now competing with the likes of Facebook, Apple, Amazon, Netflix, Google and Disney, as well as music or other audio-only services such as Spotify, TIDAL and podcast platforms, which typically use a higher Target Loudness than is used in broadcasting.

You can read more about this in our article EBU Loudness Standard Updated Including New Spec For Streaming Services.

When it comes to Loudness Range the higher the target loudness is the less headroom there is to support content with a good dynamic range. That said, most of this content is going to be consumed in noisy, or at best, less than ideal environments and so I would recommend that rather than drop the target loudness to accommodate the additional dynamic range that content destined for consumption on mobile devices is mixed with a relatively low loudness range, it which case the reduced headroom is no longer an issue.

In reality, broadcast-related content is only one part of the content that is streamed to consumers. Music streaming services are playing a greater and greater role in this sector and so this leads us to how loudness-based workflows are impacting music production.

What About Loudness In Music Production For Streaming Services?

Over the last 20 years, the phrase “loudness wars” has become enmeshed in conversations about music and audio, and for good reason.

We’ve been hearing the phrase for decades, long before we had digital limiters. We now have limiters that allow us to push level in a way that we never could before. With or without these tools, the concept of making more impactful and compelling records that contain good amounts of dynamic contrast and loudness isn’t going away. 

Given that this is the case, we should dig a little deeper into the craft of music production to think harder about what contributes to the experience of loudness.

There are two key considerations in loudness: average level and the distribution of energy across the spectrum. If you make a record focused in the upper mid-range, it’s going to be louder by definition (if the average levels are the same) than a record containing more low-frequency information, proportionally speaking.

When we talk about dynamics, whether that is dynamic range or musical dynamics, very often, what we are really talking about is contrast. We mean that something’s louder than something else—a nearby truck horn is louder than one at a distance, a verse is generally not as loud as a chorus, and the chorus is louder than the verse.

When the time comes to consider pushing the perceived loudness in a mix or master, we need to keep this dynamic contrast between sections in mind.

Is there enough of it? When we compress, will it diminish the sense of dynamic contrast?

If we are concerned about the perceived loudness overall, where is the energy focused? Is it focused in such a way that the track will appear loud enough to the listener?

So how loud do I make my track for streaming?

The question of how loud your master should be if you’re distributing to Spotify, Apple Music, Amazon Music, vinyl, and so on might be the wrong question to ask. Perhaps the right question should be…

“Can I make this louder and have it sound at least as good—if not even better—than it sounds now?”

Adjusting the way we conceptualize good and loud enables us to start to truly develop the craft and skills of mastering (and mixing), managing the tradeoffs, recognizing when we've got to the place where the music is as loud as it should be, sounding as good as it can be so when it's adjusted for playback, either turned down or if we have to turn it up for certain kinds of applications, it will still sound as good as we can possibly make it sound in that moment.

How To Measure Loudness

In the same way that, while we all recognise intelligence when we see it there is no accurate way to measure it (IQ tests aren’t accurate if that’s what you are thinking), it’s only relatively recently that we have developed a reliable way to measure perceived loudness and the resulting Loudness Unit (LU) using the BS1770 standard.

Loudness Normalisation

Once you can reliably measure loudness, you can perform Loudness Normalization and achieve that goal of ensuring that every piece of audio has the same perceived loudness.

Streaming platforms, such as Spotify and Apple Music, employ Loudness Normalization to provide a consistent listening experience for their users. By using algorithms that measure the loudness of each track, streaming platforms adjust the playback level to a standardised loudness target, expressed in LUFS (Loudness Units Full Scale) or LKFS (Loudness K-weighted Full Scale). Note that LUFS and LKFS are two names for the same measurement.

This might sound like a technical detail which, while relevant to the people producing content, isn’t something the average listener will be interested in but unlike many (most?) technical details in audio loudness normalisation has really improved the experience of the listening public. When used in broadcast or for film, loudness specs mean that the listener enjoys a more consistent experience without the need to adjust the volume during ad breaks or from song to song when streaming music. Loudness normalisation has proved to be the development which finally ended the ‘Loudness War’ where, for years, music had prioritised attention-grabbing levels at the expense of quality.

Album Normalization

The benefits of loudness normalisation have been profound, but it’s not perfect. But things are a little different when it comes to music, as opposed to broadcasting. One of the things which it assumed was that all music was supposed to be the same volume. That just isn’t the case. A full-on track is supposed to sound louder than a sparse ballad, something mastering engineers working on album projects have always understood. This has led to an approach called Album Normalisation, where artistic intention is factored in, allowing for a desired rise and fall through the duration of a long-form work.

To learn more about loudness normalisation's role in streaming, including a discussion of album normalisation, check out our podcast with Rob Byers and Bob Katz for the details from people who really know their stuff! They also look in detail at the updated audio streaming and on-demand services recommendations from the AES.

If you would prefer to read what they said rather than listen to it then in our article Loudness Standards For Music Discussed By Experts you read a transcript of the podcast.

The music distribution world has changed. Revenue from audio streaming services is higher than all other music delivery formats combined, it’s even more important to understand the impact that streaming has on audio production and how best to optimize our mixes to make the most of the way streaming services deliver our content to the consumer.

How To Prepare Tracks For Music Streaming Services

In this series of 3 articles and free video tutorials in conjunction with Nugen Audio, our own loudness guru Mike Thornton takes you through the history, why loudness is important for music, and how to prepare your mixes ready for music streaming services.

What Next?

In part 6, Using Loudness Meters For Music And Post Production, we will end the series by listing our selection of loudness meters in alphabetical order, and as we mentioned at the start, please note that this isn’t an exhaustive list. Where we have them, we will include tutorials and reviews of each of the meters.

Why Is It Now Available For Free?

This series, originally released in 2016, was on our premium tutorial channel, and since the platform they were hosted on closed down, this much-loved resource has not been available. Rather than find another platform, Mike has decided to make the entire course available completely free. We will be releasing the complete series over the coming weeks, all of which you can access completely free.

In just over 1 hour, Mike Thornton helps you understand how the new loudness standards affect you and the clients you work for. Mike has been delivering loudness training courses to broadcasters in the UK, Europe and further afield, and with this tutorial series, you too can benefit from his expertise.

Who is this course for? 
Although it is aimed at people working in broadcast and OTT environments, they need to produce content to comply with the loudness delivery specifications like ATSC A/85 for the US and Canada and EBU R128 for Europe, including live audio mixers, audio post-production editors and mixers, compliance teams, as well as video editors, and others working in the delivery of broadcast content, the first three tutorials in the course will be very helpful for people working in music production, who need to deliver loudness compliant mixes to any service using loudness normalisation.

What does the course cover?
In this series, we start by answering the question, ‘Why do we need loudness?’ We go on to cover the difference between peak level normalisation and loudness normalisation. We look at the history of audio metering and how the loudness standard has been developed and learn that the different delivery specifications around the world are, in fact, all based on that one standard. We show how to calibrate your monitor speakers, which is an essential part of mixing to loudness, before moving on to some tips and tricks on how to mix to comply with the new loudness standard and delivery specifications. 

How Much Does This Tutorial Series Cost?
This course was available for rent on our premium tutorial channel and cost $49.99 for one year. It is now available completely free at no cost.