Turn Down the TV!

September 28, 2009

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.

What’s Cooking?

September 28, 2009

Besides the use of written language, one of the most distinctive characteristics of humans, as a species, is that we cook our food.  Dr. Richard Wrangham, who is a Professor of Biological Anthropology at Harvard University, and is the director of the Kibale Chimpanzee Project in Uganda, has a theory that cooking is not only a distinctly human trait, but something that helped shaped human evolution in the first instance.

The NPR Web site has an interview with Dr. Wrangham [transcript and audio] in which he discusses his theory.  Although the origins of cooking are, as he says, lost in pre-history, there is some good evidence that people would have immediately liked cooked food, even if its discovery was accidental:

…  the reason for saying that is we have done tests on the great apes, and the great apes uniformly show a preference for cooked food over raw or sometimes have no preference for cooked over raw in the case of one or two things, but they never prefer raw to cooked.

The evolutionary question Dr. Wrangham is trying to answer is what happened that led to the development of modern humans, first Homo erectus and then Homo sapiens (us), distinct from our common ancestors with the great apes.  The most obvious biological difference is that we have very much larger brains; and this is an issue because, not to put too fine a point on it, the brain is a metabolic pig, using something like 20-25 % of the calories burned by the body.  Yet, despite the increased energy requirements of a big brain, humans have significantly smaller jaws, teeth, and digestive systems than our great ape relatives.

Dr. Wrangham’s theory is that cooking accounts for the difference.  Cooked food is more efficiently digested for several reasons:

  • It makes the food softer, so that fewer calories need to be expended to mechanically break down the food in the gut.  (Interestingly, some chimpanzees will mash some foods before eating them, presumably for the same reason.)
  • Cooking makes protein more available for digestion, by relaxing its molecular structure, making the amino acids more accessible to digestive enzymes.
  • Cooking also makes some carbohydrates (starches) more accessible, by opening up the structure of amylose and amylopectin sugar chains to digestive action.

It’s estimated, for example, that if an egg is eaten raw, about 55-60 % of the protein can be digested; if the egg is cooked before eating, then about 95 % of the protein can be digested.  So, in essence, cooking increases the “rate of return” on eating, allowing us to get enough fuel to run our large, expensive brains with a reasonable expenditure of effort.  Confirming this, it’s observed that people who try to eat a diet composed entirely of raw “natural” foods have difficulty getting enough calories.

(This also points up a flaw in the way foods are currently labeled for their nutritional value.  The implicit assumption in this labeling is that the number of calories from, say, a carrot is the same whether it is eaten raw or cooked.  Some of this newer research indicates that assumption is false.  Interestingly, this may explain in part why the increased prevalence of highly-processed foods in our diet is correlated with excess weight.)

So the next time you grill a steak, or make some scrambled eggs, be reassured that you’re just doing what comes naturally.  Of course, if you want to be an evolutionary rebel, you could always have some sushi.

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