Back in the days of analog recording, meters actually displayed electrical level as a representation of audio level. Today’s digital technology enables alternative types of metering. For example, unlike the human ear, which has different sensitivities to sound at varying frequencies (we perceive volume changes in mid-range frequencies much more acutely than at low and high frequencies), old-school level meters can’t distinguish between frequency ranges.
To account for this, engineers created an entirely new metering scale, called LUFS (Loudness Units Full Scale) to account for how we actually perceive loudness, not just average levels or peaks. (There’s a further refinement called LKFS, which uses something called weighting to account for differences in frequency response.
Loudness Units Full Scale
LUFS is a measurement of loudness units designed in line with ITU-R BS.1770 recommendation about the loudness and true-peak level of audio. The concept of a loudness unit is identical to a decibel. However, the loudness units measurement system is weighted to the real perception of audio rather than just the electrical signal. Ultimately, this has far more real world carry over. It makes the balancing of multiple audio sources far more manageable. This is because you’re metering the final product and not the electrical source of varying projects.
A good example of the practical use of LUFS metering would be when one is browsing through eclectic iTunes library or rolling through the suggested videos on YouTube only to have to continually adjust the speakers because the next song is way too loud or way too quiet? Ok, perhaps not all the time but we certainly find this to be a regular occurrence. LUFS metering system ensures that all music plays back at a consistent level. This creates an enjoyable experience for the listener. Let’s face it, the audience is always the most important person to cater to.
Different measurement units
It’s important to recognize that there’s a significant difference between the units of measurement used by VU or PPM meters (dBVU and dBFS, respectively—the “FS” stands for “Full Scale”) and those used by loudness meters (LUFS). In addition, loudness meters such as the Waves WLM Plus Loudness Meter plugin provide actual numerical readouts instead of an abstract needle swinging or segments lighting: either you hit the target or you don’t, no interpretation needed.
The Broadcast television industry uses the LUFS scale extensively. Additionally, government standards mandate consistent volumes between channels as well as when a channel goes from program material to commercials. Video games and online delivery systems also use it. Some game companies specify that the mix for a music track has to fall within defined LUFS levels. This is because they can better predict how it will balance with the other game sounds.
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