5.15.2011

To scale or not to scale?


According to the local Sunday paper, the Great Southern Brood of 13-year cicadas, aka Brood XIX, is crawling out of the ground, even as we type. From the looks of the map included with the article, it doesn't look like the inch-and-a-half long bugs (said to be akin to "flying chicken nuggets" to dogs, birds, and squirrels) frequent the Hampton Roads area much.

But what did catch my eye in the article was this graphic comparing the sound level of the cicada's mating call (from a distance of 20 inches, though I don't know why you would be getting that cozy with a cicada, unless you are another cicada) to an assortment of common (?) noise sources, placing it at 105 decibels – between city traffic's 80 decibels (from the sidewalk) and a 110-decibel jackhammer (at arm's length).

The caption text points out that the decibel scale is exponential, making the cicada "hundreds of times louder than city traffic". OK, I get exponential scales. But I was flummoxed by the curious and confusing note (in the red ellipse which I added for emphasis, and enlarged below for clarity) explaining, if you want to call it that, that the "Decibel scale is not to scale".


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