What does all of this mean?

“They” say that the typical hearing range of the human ear is from 20 Hz to 20 kHz (20 Hertz to 20 kilo-Hertz, or 20,000 Hertz).

To help put this in perspective: if you were to wave your hand back and forth one time every second, you would produce air movement that looks like this:

In technical terms, that would be called “1 Hertz”  (or, “1 Cycle Per Second”).

20 Hz (the lowest frequency humans should be able to hear) means that air moves back and forth (or, “oscillates”) 20 times every second, and 20 kHz (the highest frequency we should be able to hear) means that the air oscillates 20,000 times every second.

Why does this work?

Even though “they” say humans can hear from 20 Hz to 20 kHz, most of us can’t. As we get older  (I know, I know - you’re still 29...), our hearing starts to weaken, and we stop being able to hear the really low sounds or the really high sounds (if we ever could that is).

Typically, middle aged people’s hearing range shrinks and they can hear only up to 12 or 14 kHz while their annoying teenaged offspring can still hear it all.

Therein lies the secret to this program! By playing tones outside the hearing range of most adults but within the hearing range of most teens, we can successfully produce a weapon that’s agonizing to (most) teens and completely ineffective against (most) adults.

Now, I know there are a few adults out there than can still hear these high pitches - some even higher than my own hearing range - and frankly, I’m jealous!

What exactly is this app doing?

When you choose a frequency in this app, you are given the choice between many frequencies between 15 and 18 kHz. At these frequencies, the air moves back and forth too fast for adults’ ears to pick it up as sound. To give you an idea of just how fast this is, look at this graph of how the air moves back and forth in one hundredth of a second:

When you play a “continuous tone” in this application, what it’s doing in the first second looks like this:

Now THAT’S fast! Really the only thing you can see from the above is that it fades in to prevent a “pop” sound - but, other than that, it’s just a bunch of air moving.

When you play a “slow pulse” in this application, it looks like this: (repeated over and over and over and over.....and over again)

The “fast pulse” is the same thing, except it does this in 0.8 seconds and repeats.

Now don’t go away - I have another surprise lurking around the corner that we’ve had so much fun playing with and trying to get to work right!