CALM and Audio Loudness on TV
by Leslie Ellis // July 20 2009
Maybe this has happened to you: You’re multi-tasking a nap with some TV. You’re right at that drifty spot between awake and asleep. Then, the ear assault: BIG AL! REALLY DOES! SELL CARPET! CHEAPER!
Congresswoman Anna Eshoo (D-Calif.) found this bothersome enough to create a piece of legislation around it (H.R. 1084), called the “Commercial Audio Loudness Mitigation Act,” abbreviated “CALM.” It calls for the FCC to set standards for audio levels in commercials played on broadcast, cable and satellite TV.
Let’s start with why such audio level variations happen in the first place. It’s a dynamic range issue, compounded by compression. Dynamic range, in audio, is the continuum of sound, from the softest you can hear, to the loudest you can tolerate.
What’s being compressed is that range. In a big oversimplification, the producers of TV advertisements run the audio track through a machine that adjusts all sound to its peak level. No quiet spots, no pianissimo. Everything ratchets up to loud.
How to fix it? It’s not a no-brainer, partly because people perceive loudness differently. Surely you have the person in your family (hi Dad) who turns the TV up way too loud for your comfort.
Plus, audio level variations manifest within and between video channels: How you hear loudness between a program and an ad on one channel, and how you hear loudness between that channel and the next.
One approach, developed by Dolby, listens for and calibrates audio to a dialog level — the level at which you and I would talk comfortably to each other, if we were in the same room right now. Explosions, shouting, and music are normalized relative to conversational levels, not the other way around.
This week, the Advanced Television Systems Committee — the technical standards-setting body for over-the-air TV — plans to submit a recommended practices document on the audio matter to its governing members for review. The thinking: Work collaboratively to solve the problem; skip the act of Congress.
Or, put another way, stay CALM.
This column originally appeared in the Platforms section of Multichannel News.