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 the end product. Curtis Judd breaks down both the techniques for, and the thinking behind, managing loudness in your audio.

1. Volume vs Loudness

First, Curtis 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)
'Volume vs Loudness - LUFS & LKFS for Measuring Loudness for Video' | Curtis Judd
‘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

2. 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: