Loudness - From your old Receiver button to the streaming platforms : Blog

During the last decade, the development of audio mastering has been involving a new, important concept. The concept isn't new, though. Those who used to have CD or even vinyl players remember a button called " Loudness " that slightly increased sound pressure. In general, the button added punch and light compression to bass sounds so the audio wouldn’t fade completely when quiet or blow up when loud. Nowadays, it is one of the most important terms related to professional audio. It nominates a unit of measurement included in every modern production, LUFS. More than that, it relates to the notion of a standard of finalization to apply in audio production, demanded by platforms such as TV and streaming services, each with its requirements. If you’re mastering a track it’s important to pay attention to this, no matter what medium you’re producing it for.

What is the current meaning of loudness?

It refers to the level of compression of a track.
We speak of loudness when talking about the adequate mastering level for each streaming service or store. Nowadays there is an automatic adjustment based on RMS volume, so there’s no reason to master (aka compress) at more extreme levels than those since the volume of the song will be lowered as a whole. If you try, though, you’ll see that the track will sound worse and less dynamic in comparison to other tracks, even if it is more compressed.
LUKS is the unit that indicates the adequate levels for broadcasting, based on the length of the program and the audibility curve of human hearing. It’s described in dBFS.

What is loudness?

In English, “loudness” refers to the sensitivity of the human ear concerning the range of volume of a sound, going from quiet to loud. Recently, Loudness started being used to describe this intensity standard adopted by audio productions, whether they be musical or cinematic, broadcast via TV or the internet.

This standard is based on sound scale measurement units used for many years in the industry. So, to understand Loudness, we need to quickly review some of the most important measurement units used in the sound field.

Decibels

DBFS or dB FS (Decibels relative to Full Scale) is the unit that measures amplitude (aka volume) in digital systems. The dBFS scale, unlike any other, goes from “-∞" to “0”. Meaning it includes only negative numbers and 0 dBFS represents the maximum volume on this scale. Try going beyond that and you'll get a clipping effect. In other words, the sound will blow up and become saturated and distorted, with much lower quality. This usually isn’t what one tries to achieve during a recording.

The dBFS is a digital decibel reading, existing since the emergence of the CD, which was already a digital medium. Nowadays every recording released digitally, whether they be CDs or streaming platforms, goes through measurements based on dBFS during the finalization process. The LUFS (Loudness Units Relative to Full Scale) is based on the dBFS - we’ll talk about it in a bit. Ever since the invention of the CD and the moment when dBFS started to measure masterings, the trend in audio production was to make everything louder. This phenomenon played a key role in the development of the famous Loudness War.

Beware: don’t mix up dBFS and dB SPL. dBFS only exists in the computer and is used as the track is being completed. The dBSPL, however, refers to the Sound Pressure Level, the unit that measures the degree of sound pressure in space. Therefore, it’s used to measure sound reproduction in sound boxes or sound volume as it arrives at a person’s ear. You'll never "hear" dBFS nor will you have dBSPL inside your DAW.

Loudness War

The "loudness war" reached its apex between the second half of the 90s and the second half of the 2000s. Sound engineers and producers all over the world started to gradually increase the audio signal until it reached its peak: 0 dB (full scale, remember?). CDs in that period got louder and louder. The same happened with basically every sound produced for TV, cinema and radio. To increase the level of the signal basically means to decrease the distance between the peak and the RMS.

What are peak e RMS levels?

A musical signal has many variations in its frequency. The peak is the highest power achieved. The RMS (Root Mean Square) is a kind of medium level. The terms “peak” and “RMS” come from engineering and have always been used in other fields of knowledge. Equipment manufacturers embraced RMS as the norm for speakers’ power and peak for power amplifiers. With the emergence of the dB FS for audio finalization, RMS and peak started to also represent the levels of sound dynamics.

Let’s go back to the Loudness War for a moment: if RMS is (kind of) in the middle and peak is the maximum, we can confer that peak refers to the punches included in the track, while RMS represents the medium, uniform volume of the song. The variations between RMS and peak differ according to the dynamics of the song, right?

That’s exactly where the war started.

To make the sound louder, sound engineers started to continuously increase the RMS of the track. Since the peak couldn’t go over the maximum - 0 dB FS - the compressors and limiters were badly abused. RMS and peak got way too close to each other, reducing the Dynamic Range, the proportional interval between higher and lower values in a sound signal. If you looked at the tracks on the screen, you’d notice they’d become almost straight, with fewer highs and lows.

The compact disk era reintroduced many classics originally released in vinyl to the market. The remixed discs followed the new standards, becoming victims of the war. Try to notice the change in the medium volume rate in “Something”, by the Beatles.

loudness level of track "something" by the beatles in 1983

loudness level of track "something" by the beatles in 1987

loudness level of track "something" by the beatles in 1993

loudness level of track "something" by the beatles in 2000

Taking a look at the careers of many artists, such as Metallica and Foo Fighters, one can notice the change brought by this trend. Californication (1999), by Red Hot Chilli Peppers and Back to Basics (2006), by Christina Aguilera, are infamous examples of the Loudness War.

On behalf of tradition, classical music doesn’t use compressors in digital recordings.

Why is Loudness War bad?

Because of the excess of compressors, equalizers, limiters and other components used so the peak doesn’t go over 0 dB FS. All of those crumple up the frequencies and peaks, damaging the final quality of the production. The result sounds less dynamic and with no peaks. Such an intense sound becomes tiring to hear. This can be more easily noticed in the voice and the guitar;
If the RMS is always on high, it disrupts the dynamics of interpretation and expressiveness of a performance. Since it is poor in nuances, it loses feeling and intention.
In lower-quality equipment, some frequencies may even sound distorted.

The boom of music video productions for TV also contributed to the emergence of the Loudness War. TV stations themselves were one of the first groups that started taking important actions to normalize sound levels. The growth of the internet brought to the world boundless music distribution, demanding discussions around the matter as well. At the same time, new mediums of sound reproduction, such as notebooks, smartphones, tablets and different kinds of speakers became more widely available.

LUFs/LKFS

The intensity scale created to normalize audio levels on TV and video in general is the LUFS (Loudness Units relative to Full Scale). It’s also called LKFS (Loudness Units K-Weighted relative to Full Scale), arising after discussions held in 2006 in the ITU (International Telecommunication Union). The ATSC (Advanced Television System Committee) and the EBC (Europea Broadcasters Union) later improved them.

Known as smarter than the RMS, the LUFS uses the dB FS scale as a “ruler” - that is, it measures values in dB FS. But the unit is defined by logarithm calculations. These calculations consider the human audio perception, enhancing medium and high frequencies above 2000 Hz, the most significant range we can hear. These calculations follow mostly the human audibility curve, represented by the Fletcher Munson curve. Ever since the publication of LUFS, many TV channels and radio stations in the world established a baseline established around this measurement to use in their sound productions. Most streaming services, such as Spotify and YouTube have also established their standards in LUFS.

Nowadays, it’s common to finalize a track with many different versions in a studio, each fulfilling a certain purpose. Even if the track sent streams at a rate different from the required standard, the platform will convert it (and this can damage sound quality).

Apple Music: - 16 LUFS
Youtube: - 14 LUFS
Tidal: - 14 LUFS
Spotify: - 14 LUFS
Netflix: - 23 LUFS

Ready to give the final touches to your production? Loudness varies from one platform to the other. The idea is to use the concept in a way that benefits your music.

Loudness – From your old Receiver button to the streaming platforms