Decibels

‚ÄčThe measure of amplitude or power of sound waves is expressed in decibels (dB). For most of the things we measure in life, we use linear scales. Assume you place something that measures 15kg (roughly 33lbs) onto a scale and then added an  identical item. The combined weight would be 30kg (66lbs). However, the dB scale is logarithmic, which means it is not directly additive when combining quantities. 

Assume you have a device that generates 60dB of sound pressure, which is the normal volume of a television in the home of someone under the age of sixty or the peak volume of a polite conversation amongst sober people over the age of twenty-five. If you turned on an identical machine, the sound pressure level would double. Linear logic would lead you to believe the combined noise would measure 120dB but that is wrong. The measurement would only rise to total 63dB. The doubling of power in a sound wave results in an increase of 3dB. This is the case for all physical devices that create sound with one exception: children. More specifically, boys.

Assume you have one boy, who is making noise at 85dB, which is the same sound pressure level of your average freeway from 10m (32.75ft) away. If you add a second boy making noise at the same sound pressure levels, the normal rules of acoustics would dictate an increase of 3dB. However, in the case of boys, the increase of sound pressure level is closer to, but not exactly, 15dB. Meaning two boys are capable of a sound pressure level similar to that of a jackhammer without even trying. What gets harder to explain is when you add a third boy. Adding a third boy capable of the same noise as the first two will increase the sound pressure level by another 30dB. I don’t mean 30dB total, I mean 30dB in addition to the 15dB added by the second boy. This means three boys, with very little effort, can generate a sound pressure level that reaches the pain threshold of the average human ear and, at the prompting of a good fart joke, can be as loud as a jet airplane leaving the runway. Add a fourth boy and mention the word “poop” or “butthole” and you’ll be lucky if you don’t suffer instantaneous, irreparable hearing loss. 

This message is meant as a public service announcement. Please take care of your ears and wear proper hearing protection devices if you’ll be around more than one boy at a time. The headsets worn by airport workers on the tarmac should suffice, unless one of the boys burps.

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