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)

• 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:

Audio School: Loudness, Normalized

Further Viewing

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

Film School: Mixing Audio in Premiere Pro

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

Film School: Advanced Audio in Premiere Pro