Audio School: Loudness, Explained

'33 Beautiful Examples Of Volume Dial And Knob Designs' | Hongkiat '33 Beautiful Examples Of Volume Dial And Knob Designs' | Hongkiat

How to understand, measure, and even out the sound in your video project.

Inconsistent audio levels present challenges – both for the video-maker in post-production, and for the viewer watching (or, more specifically, the listener hearing) the end product. Here’s a quick look at sound versus hearing, followed by techniques for, and the thinking behind, managing loudness in your audio.

1. How we hear

In under 8 minutes, Tom Scott breaks down the science of sound versus the neuroscience of hearing (and, along the way, the audio regulations of platforms like YouTube and Spotify):

2. Volume vs Loudness

Curtis Judd first explains the difference between Volume and Loudness:

Some takeaways from this initial explanation:

  • Volume is what the viewer / listener can adjust, while Loudness is the amount of sound available for that adjustment
  • Loudness comprises:
    • Amplitude – the height of the peak in a waveform
    • Sustain – how long a waveform at a certain amplitude lasts over time
  • Loudness can be measured by:
    • dB RMS – more technically correct, but less useful; an average of amplitude over time (including silence or gaps in sound, which compromises accuracy)
    • LUFS or LKFS – measures Perceived Loudness, or the way we as humans hear; a more useful metric (which doesn’t include stretches of silence in its averaging)
Audio School: Loudness, Explained
‘Volume vs Loudness – LUFS & LKFS for Measuring Loudness for Video’ | Curtis Judd
  • Television broadcast has standard loudness limits or “targets”:
    • EU: -23 LUFS
    • US: -24 LKFS
  • Online streaming has no unified standard:
    • YouTube and Spotify: -14 LUFS

3. Loudness Normalize

With Loudness defined, Curtis then explains the concept of how to normalize, or create consistency throughout, the loudness of your audio:

Further Viewing

As demonstrated, loudness is best managed after you’ve mixed your audio:

Here are some more advanced tips for mixing audio for video:

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