Terms like LUFS and RMS can seem confusing when you’re recording, mixing, or mastering audio. However, once you understand the difference between them, these tools can be used to give you greater control over your audio’s dynamics.
LUFS and RMS are two tools that can be used to gauge the average level of audio. The key difference between them is that LUFS can be used to get the level of an entire recording, while RMS is better suited to smaller sections of audio, generally up to a maximum of 300ms.
This may sound complicated at first but understanding LUFS and RMS becomes much easier as you learn about the ways that they can be used. If you’d like to become a better audio engineer, these two tools will likely become an essential part of the process.
This article will explain the differences between LUFS and RMS and how you can start to use them to enhance the sound of your audio.
What are LUFS and RMS?
LUFS stands for “Loudness Units references to Full Scale”. It was introduced as an audio standard in 2011 by the EBU (European Broadcast Union) in an attempt to ensure that TV programs were consistent in volume.
RMS, on the other hand, is an abbreviation of “Root Mean Square”. Technically, it is a measurement of voltage levels used for electrical signals and is commonly used to indicate the maximum continuous power that can be fed into an amplifier.
Unless you’re quite experienced in the world of audio engineering, you’re more likely to have heard of RMS as it is used in the specifications of speaker systems. LUFS is more exclusive to those working in the professional audio mixing industry and here is a variety of audio mixing boards on amazon.
These two tools are often grouped together because, on the surface, they can be used for the same purpose. LUFS can tell you the average level of a full piece of audio, and it has no maximum time limit.
RMS is used to indicate the average volume of a short segment of audio, generally up to 300ms.
When mixing or mastering audio, you don’t need to choose between one or the other. The best results are achieved when RMS and LUFS are used in conjunction with one another – as this gives you the best indication of dynamic consistency.
LUFS was introduced by the EBU in 2011 to improve consistency in the loudness of audio used on TV. The way that this is determined involves a process known as “K-weighting.”
K-weighting involves filtering audio in a way that is similar to the way the human ear experiences sounds at different volume levels. Equalization is used to replicate the inconsistencies in the way our ears hear the different frequency bands that make up a sound.
Without getting too technical, LUFS results in a new version of a piece of audio, which has been equalized (EQ) to match the way the human ear hears it and can then be measured with a maximum digital ceiling of 0dBFS.
LUFS can therefore be used to gauge the average level of a full song, which is why it’s a great tool for mastering music.
Popular streaming platforms automatically reduce the volume of any music which exceeds their maximum average level. They use LUFS to determine the average, with -14LUFS being the optimal average.
Mastering your music or other audio to -14LUFS will ensure that it is consistent with the other music on streaming platforms.
Rather than being used to gauge the average level of a full song or entire piece of audio, RMS is most commonly measured at 300ms. Nevertheless, like LUFS, it can be useful for gauging the average loudness of the audio.
RMS is used to indicate the continuous power handling capabilities of a speaker or a subwoofer. It can also provide you with the maximum continuous power that can be output by an amp.
However, in music production and mastering, it is a valuable tool that can be used alongside LUFS to get an even more accurate average loudness of a piece of music.
The RMS and LUFS readings that you get are likely to be very similar. If there’s a considerable difference between them, then this indicates that the audio has a wide dynamic range. Audio that has been heavily compressed and limited will provide you with almost identical RMS and LUFS averages.
What is The Loudness War?
If you’re interested in mixing and mastering music, you may have come across the term “loudness war”.
Before the shift to digital streaming platforms, which provides some regulation on music volume levels, audio engineers around the world were mastering songs to the maximum dB that they could.
The louder the average song became; the more engineers followed the trend. That had a knock-on effect for many years and resulted in a lot of music sounding, in some people’s opinions, overly compressed and limited.
When a song is mastered to a very high level, the peaks and troughs of the audio waveform are normalized. This results in less dynamic range and more of a solid block of sound that is constantly loud with minimal variation.
Although this consistent loud sound may be desirable for certain styles of music, particularly music used for raves and nightclubs, it perhaps isn’t ideal for other genres like pop or rock.
On another note, the loudness war, very likely damaged a lot of people’s hearing, as songs became much louder for longer periods of time. Listeners could be listening to one song on a lower volume, then suddenly, another song could come on that was much louder before they had a chance to adjust the settings on their device.
This problematic phase was thankfully brought to an end when streaming platforms like Spotify and Apple Music came along and began to act as a regulatory body for the average loudness of songs.
These platforms normalized the volume, which meant that if a song was louder than the LUFS level they established, it would automatically be brought down to within the predetermined window.
Music is now mastered to keep it within the confines set by Spotify and other streaming platforms, and the loudness wars are now a thing of the past.
What is a good RMS level?
An optimal RMS level to aim for when mixing and mastering music is between -7dBFS to -12dBFS. This will ensure that the audio has a good balance between being too compressed and being loud enough.
How do I raise my RMS level?
To increase the RMS level, you’ll need to reduce the dynamic range in the audio. This can be achieved by using a limiter or a compressor to make the loud parts of the track quieter and vice versa.
How do I stop my master from clipping?
If you are experiencing clipping when mastering audio, this is because you haven’t left enough headroom in your mix. You’ll need to go back and reduce the overall volume of the track, then attempt to master it again.