Although reasonable people understand that it is advertising, in the form of commercials, that pays for broadcast television that is free to watch,we still find commercials to be distinctly annoying at times. I can remember, when I was still a kid, asking why the commercials on TV were louder than the program, and being assured that they weren’t — that FCC rules required them to be no louder than the program. Although there was some truth in that claim, my ears were telling the truth, too. Now, according to the “Physics Buzz” blog at the Physics Central Web site, there is a move afoot to make this aspect of commercials less annoying
As I mentioned, there was some truth in the claim that.FCC rules mandated that commercials be no louder than the programs associated with them. As is often the case with regulations, however. what I call the “Chicago Election Axiom” came into play: it’s not the voting that counts, it’s the counting that counts. What the rules actually say is that the peak audio amplitude in the commercials must be no higher than the peak amplitude in the program. (Both must be less than an overall limit.) The problem is, it is entirely possible to stick to the letter of the rule while making the commercials seem louder (and therefore, presumably, more attention-getting), because the rule does not reflect how human hearing works:
The problem with this approach is that the peak level of the sound does not accurately reflect how loud something sounds to the listener. Our brains judge loudness by averaging all of the waves that roll by — big and small.
Furthermore, our hearing is not uniformly sensitive at all frequencies. Notionally, the range of sounds audible to humans ranges from 20 Hz to 20 kHz. But very few adults can hear out to the highest frequencies, and everyone’s hearing is most acute in the middle frequencies.
Audio engineers also recognize that human beings have evolved to pay more attention to certain pitches that have been important for our survival.
“We are most sensitive in the mid-range, in the range of babies crying,” said David Weinberg, chair of the Washington D.C. chapter of the Audio Engineering Society.
The producers of commercials can boost these frequencies, without raising the peak audio level, to make the commercial subjectively louder. They can also compress the dynamic range (between soft and loud sounds), again raising subjective loudness without breaking the rules. Although audio processed in this way sounds harsh, and is unpleasant to listen to for any length of time, we can tolerate it for the 30 or 60 seconds of the typical commercial.
The new rules, if approved, will require digital audio content to be tagged, so that electronics in the receiver can “undo” any unnatural signal processing:
The new audio recommendations, soon to be sent out to broadcasters for approval, provide a way to measure the loudness of television content based on current scientific understandings of how human hearing works. Shows and commercials would be tagged with information about their loudness that TVs and audio receivers could use to counteract the audio tricks that make commercials jump out at us.
If nothing else, adoption of the new rules might produce some slight reduction in fighting over the TV remote.
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