As an engineer, I hear a lot of terms that I cannot translate easily. This is because what some may call too quiet, someone else may say is too loud. Turn up the volume or turn it down! That's not as easy to do as you might think. Even engineers use terms like this, words that are difficult to measure much less understand. Sometimes it is for good reason, those words are meant to describe emotion, that cannot be measured.
So let's discuss one of the most important words in audio engineering, Loudness, and how we speak about it, measure it, and use it to our advantage.
VOLUME
A scientific definition of Volume would go something like this: the amount of space occupied by an object. In this way, Volume is for the most part fixed. In audio terms, Volume is described as the degree of loudness or intensity of a sound. Volume in audio as you are well aware is not fixed.
As an audio engineer, the term Volume is not a term I use because it isn't really relevant. Audio engineering is all about controllable variables, metrics that mean something, or terms that can never be measured. I may say that compressor is really leveling-out that track, which can be measured by gain reduction, but I don't substitute words like volume for tangible words like Loudness.
There are of course a lot of intangible terms or subjectivity in audio engineering. Compression “glues-together” a drum bus or adds "warmth'; Saturation adds “color”; higher frequencies add “air”. But these are terms used to describe something that really cannot be measured at all. Volume is simply a replacement for Amplification or Loudness that some may find difficult to express in engineering terms.
So we live in a world where words mean something, perhaps only to the individual, but really have no way to be described in exactly sometimes. So lets stick to the words we can measure for this topic.
RMS v. LUFS
Loudness is a very useful term to an audio engineer. It is typically measured in two common forms: RMS and LUFS.
RMS or Root Mean Squared is used to measure the “average” of continuous, varying signals, such as audio, electrical signals, etc. It is a useful way to measure by numbers the Loudness of a signal. But RMS lacks the advancement that we have achieved with LUFS. Specifically, it doesn’t account for how humans perceive Loudness. In its purest form, RMS is simply a rolling average of Loudness depending on the duration of audio used to determine the average.
LUFS on the other hand, Loudness Units (relative to) Full Scale, also averages sound like RMS, but it includes the perceived level of loudness in its calculation. Decibels measure the level of air pressure generated by a sound, whereas Loudness Units factor human perception as well as electrical signal intensity. LUFS is also considered the standard for Loudness on most streaming platforms.
I don’t really use RMS - unless I am forced to - and the same goes for VU meters. But the whole reason we are discussing this here is because some plugins and DAWs provide RMS and LUFS meters. It is important to know why both exist, but it is not critical you use both.
Notice here I am employing LUFS and True Peak in my MultiMeter. Since I don't use RMS, I only care about my Peaks and LUFS.
LOUDNESS YESTERDAY
You may have heard of the Loudness Wars. It started a few decades ago as engineers began pushing audio as far as possible in an effort to have their songs played louder - without an increase in your radio volume dial - than the other songs it was competing against. Much of this was amplified by the digital revolution in audio production.
Loudness is also a great way to really drive a sound source. In my work, Loudness is one of the most critical parts of a song. Without a noticeable degree of Loudness, some songs just don’t elicit the kind of emotion I want depending on the recording.
The Loudness wars raged for quite some time, engineers are still battling today, but their efforts are hardly appreciated like they were 10-20 years ago. This is because while there were standards for Loudness, they weren’t enforced like they are today. Now your song may not get through on a streaming platform without being applied to a LUFS regulator.
LOUDNESS TODAY
If you plan to submit your music to any of the popular streaming site, and if the listener has Audio Check (iTunes) or Audio Normalization (Spotify) checked, which are turned-on by default, chances are your song will be limited to a maximum of approx -14LUFS.
Fact is, most people listen to music through headphones or ear buds, so it makes sense they would limit the maximum Loudness of all audio. Running headphones directly from an iPhone will give you an acceptable level of Loudness, and frankly -14LUFS is really loud enough at max volume for most headphones today. So limits on LUFS are really just a way for the streaming services to keep amplification levels in check.
To the distinguished listener, however, normalization is a four-letter word. I always turn it off. To mixers and masterers, normalization is an unfortunate reality.
For me, I actually don’t care about Loudness until mastering, I let my ears decide how loud my project is going to get. And even during mastering, it may not make that big of an impact either. Of course my mixes and masters are always kept below digital zero to avoid clipping or distortion, but Loudness receives zero consideration until mastering. My mixes average around -7 to -10LUFS after mastering. And usually I am not pumping the hell out of my limiter to get there.
LOUDNESS PENALTY
There is no “penalty” for publishing your songs hotter than -14LUFS. But what happens if you send your -7LUFS song to Spotify? Well, if the listener has normalization turned-on, they simply reduce the gain until it is at or below -14LUFS. It should be noted here each of the popular streaming sites has its own normalization rules for Loudness, even Peak, so before you ship-off your latest song to them, be sure you know what to expect. Or do like I do, ignore their rules.
So in one sense, yes, you do get penalized for exceeding the Loudness standard of the streaming service. But frankly, with each of them having such different standards, I am not inclined to really care either...
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