We’ve already told you about things that pass under our feet without us realizing it, but did you know that there are also sounds, which pass through our ears, without us ever being able to hear them? hear ? Nope ? Well… Read this top, you might be surprised!
1. Ultrasonic dog whistles
The reason is very simple: human beings do not hear beyond 20 kHz, these whistles emit sounds between 23 and 45 kHz (which is the limit of what can be heard in our little furballs). When we blow these whistles, we hear nothing, but they do. So be careful not to abuse it… Would you like to have a high-pitched cry screamed in your ear for long minutes?
2. The Sun
BUT WHAOOOOOOAAAA? How does the sun make noise? Well, imagine that yes, he even does a lot! Like… Really a lot! Its noise is such that, according to researchers, if we could hear it, then we would never have been able to develop speech. Here, here. Fortunately, the sun is 149,500,000 km from us. If you want a little taste of the sound the biggest star in our system makes: NASA has reconstructed its sound based on 40 days of data.
3. Bat echolocation
To locate themselves in space, bats emit ultrasonic sounds, between 20 kHz and 200 kHz (that is, well above what we can hear). The echo then bounces off the various obstacles and comes back to them, which allows them to understand the environment, without actually seeing.
4. Sperm whales
Sperm whales emit different sounds: infrasonic, ultrasonic and some, in-between, that we perceive. In fact, researchers believe that the intensity of these sounds allows them to stun their prey before eating it. Same technique on the side of whales, which use sound to burst the blood vessels of their loot. As much to tell you that we are not unhappy to live on dry land, after all. Lazy to lose my eardrums before getting eaten, in fact.
5. Rocket infrasound
Unlike bats, which we cannot hear because the sound is too high (high-pitched): this is infrasound, that is to say, sounds too low (low) for we can perceive them. Yes, a sound can be too low (too low) to be heard, while remaining incredibly loud in terms of volume. You understand ? In short, in addition to the noise that we can hear when a rocket leaves the Earth, it also generates low frequency sound waves, detectable only with special instruments. To prove it to you, researchers accelerated the recording of the launch of the Atlantis shuttle 250 times in 2009. Result? They made the imperceptible, perceptible! Yes yes ! The video is just below.
6. Elephant dialogues
In the 1980s, researchers discovered that elephants were able to communicate over… 10 km! For this, they use infrasound, generally located between 1 Hz and 20 Hz. In fact, we cannot hear them, but they can discuss in scred. Truly the most stylish animal in all of animal history.
7. The sound of alarm devices
Obviously, we are not talking about the alarm that goes off in the event of an intrusion or theft. No, that fucking ringing that wakes you up every other morning because your neighbor’s car rings at the slightest gust of wind is audible: there’s NO DOUBT about it. There, it is more a question of motion detection, in home security systems. In fact, these are ultrasounds, located between 30 kHz and 50 kHz, which are emitted permanently, and which bounce off obstacles. When returns are normal and customary, no worries. As soon as someone breaks in, the infrasound bounces off the person, the wavelength is reduced (and therefore unusual) and the alarm goes off! Damn, what technology. That’s crazy.
8. Volcanic eruptions
When a volcano erupts, it never does so silently. On the other hand, the sound that we perceive is only a part of that emitted. In fact, volcanoes emit infrasound all the time, recorded and processed by stations to determine the characteristics of eruptions, or simply to monitor changes in lava levels and warn of dangers.
9. Sound Weapons
Ok, so that’s the very scary and creepy point of this top. After chemical weapons, which are already quite atrocious, did you know that there were also sound weapons? Basically, we can’t hear infrasound and ultrasound, but we can feel them. And, like the sounds we can hear, those we don’t hear can also make us feel uncomfortable when they are loud. They can even cause serious internal damage. I’m not giving you a diagram: the weapons thus consist in emitting these sounds, until the target people are hit without realizing it. Infrasound, more benign than ultrasound, is used by some countries to dissolve manifestations, for example. Horrible.