LO.8 Deliver audio compling with industr loudness metering standards

For this LO I needed to do some research to get my head and ears around what the industry standards are for loudness metering.  Runstein and Huber describe this area of audio production quite well and state that ” Like most things in life that get out of hand from time to time, the level of a signal can vary  widely from one moment to another. For example, if a vocalist gets caught up up in the moment and lets out an impassioned scream following a soft whisper passage, you can almost guarantee that the mic’s signal will jump from its optimum recording level into severe distortion…ouch! Conversely, if you set an instrument’s mic to accommodate the loudest level, its signal might be buried in the mix during the rest of the song. For these and other reasons, it becomes obvious that it’s sometimes necessary to exert some form of control over a signal’s dynamic range by using various techniques and dynamic controlling devices. In short, the dynamics of an audio program’s signal resides somewhere in a continuously varying realm between three level states;

  • Saturation
  • Average signal level
  • System/ambient noise

Amplifiers, magnetic tape and even digital media are limited in the range of signals that the can pass without distortion. As a result, audio engineers need a basic standard to help determine whether the signals they’re working with will be stored or transmitted without distortion. The most convenient way to do this is to use a visual level display, such as a meter. Two types of metering ballistics (active response times) are encountered in recording sound to either analog or digital media:

  • Average (rms)
  • Peak

For this LO, I mastered a stereo version of the Blue Lotus recording in the C24 studio. For the same mastered version of Blue Lotus, I then took the session and applied a WAVES WLM loudness plugin to apply and ensure that the correct Industry Loudness units relative to Full Scale (LUFS) could be managed and applied.

(see screen shot) 

To expand on this area, I did some further research on the Loudness metering and found this article from The Audio Producers Guide.com ver insightful and helpful and think it should be shared.

“The most common way to represent audio is to display electrical level. That usually means a waveform, a VU meter, or a peak meter — those bouncing bar graph meters ubiquitous in digital audio. The problem? These tools don’t correspond to how the audio actually sounds to our ears. It’s possible for the audio to look one way on these meters but sound quite different. Phone tape is a frustrating example of this phenomenon: on a peak meter it often looks hotter than it sounds. Modern recorded music often displays the opposite effect; it will sound louder than it looks on a peak meter, especially when matched up against voice.

Loudness meters measure audio similarly to the way humans perceive sound. The meters analyze audio taking into account duration as well as frequency — the human ear is sensitive to some frequencies (the wail of a baby, the rustle of leaves), not so sensitive to others (the rumble of a bus, the low notes of a bass guitar). That measurement is much more consistent with the way we hear. Sounds that we hear as “loud” display higher on the meter and vice versa.

The unit of measurement, the Loudness Unit [LU], actually represents an audible difference. A change of one LU is a difference you can noticeably hear — you certainly can’t say that for one dB, the unit used on most other meters.

Loudness meters also remove an issue that other meters are prone to perpetuate: interpretation

The audio producers guide to loudness



In addition to this, i think this youtube post on the industry & legal loudness standards is a very good video on explaining the LUFS values.




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