DID YOU KNOW: the loudest a sound can be (on earth) is 194 decibels?

By definition, something that is 0 dB is giving off a sound that is just detectable to the human ear. Softer sounds get negative dBs, louder sounds get positive dBs. A 10 dB increase corresponds to a doubling in loudness, meaning that, for example, something that is 30 dB is twice as loud as 20 dB and three times as loud as 10 dB.

So why is the upper limit the very specific loudness of 194 dB? Because sound is vibration. More specifically, it’s longitudinal waves. It’s like if you took a slightly stretched slinky, laid it out straight, and then rapidly pushed in and pulled back on one end of the slinky. The compressed metal spirals would move along the slinky’s body. That’s a longitudinal wave form.

For sound, this “compressed slinky” is compressed air (or whatever medium we’re in) and the compressed parts are parts of higher pressure (the expanded parts are parts of lower pressure).

Once we’re to the point that we’re hitting 194 dB, we’re at the threshold where this pressure wave switches to a shock wave. The energy is no longer moving through the air but is instead pushing the air outward. The “wave” becomes so extreme that the low pressure regions no longer have any molecules of air left in them to continue the push of the wave. All the molecules just move outward at once. It’s no longer technically sound as we define it in wave form. For example, the atomic bombs dropped on Hiroshima and Nagasaki were likely well over 200 dB and thus created shockwaves.

Also, if a shockwave is strong enough, it can freaking liquify you.

Isn’t that fascinating?

One of my old NaNoWriMo projects was about some guys trying to engineer the perfect sound that would resonate with the human body, but they get hooked on the euphoria they experience by this sound and continue to increase its intensity and volume and eventually kill themselves with it.

Y’know, just another one of my cheerful NaNo topics.

Anyway. Super cool, huh?