5 Sounds You Probably Can't Hear


Think you have perfect hearing? There are still plenty of sounds in the world that you can’t detect. The low range of human hearing starts around 20 hertz, and tops out at about 20,000 [PDF]. By contrast, bats can hear ultrasonic sounds with frequencies up to 110,000 hertz. Other animals, like elephants, hear sounds many times lower than those a human can perceive. And as people age, their hearing gets even worse, eliminating even more sounds from the range of audible noises. Here are just a few sounds most people are missing out on: 

1. Sounds for young people 

As humans age, their hearing changes. Age-related hearing loss, called presbycusis, means that older people can’t hear some high-pitched sounds they would have heard in their youth. Most people over the age of 18 cannot hear the 17,400 hertz tone in the video above. 

2. Music designed for cats

In 2014, activists from Pussy Riot rigged an electric piano to play music designed specifically for cats. Cats possess ultrasonic hearing, meaning they can hear a much wider frequency of sounds than humans (or most other mammals, for that matter) can [PDF]. Although people could hear portions of the concerto Pussy Riot staged to protest Internet censorship, the melody is a whole lot more complex from the feline point of view. For what it's worth, the cats seemed to enjoy it. Research has shown that cats are pretty into feline-specific tunes, in general. (We have some video evidence.) 

3. A dog-specific Beatles’ song

In the Beatles’ song “A Day in the Life,” the band included a whistling noise at a frequency of 15,000 hertz right after the last chord of the song, designed to be heard by canine Beatles fans. “We’d talk for hours about these frequencies below the sub that you couldn’t really hear and the high frequencies that only dogs could hear. We put a sound on Sgt. Pepper that only dogs could hear,” Paul McCartney told the BBC in 2013. (The sound starts just after the 5-minute mark.)

4. Ultrasonic finger friction

Image Credit: iStock

When you gently rub your thumb and index finger together, the friction creates an ultrasonic signal [PDF]. The action is a useful way to test out the function of a bat detector, which converts ultrasonic sound from bat echolocation into noise humans can hear. In the book Insects Through the Seasons, entomologist Gilbert Waldbauer writes that pet bats can be trained to respond to the sound, and fly toward it. 

5. Infrasonic elephant calls 

Image Credit: iStock

Elephants can hear and make sounds well below human range, to as low as 14 to 16 hertz. They can also produce these infrasonic calls at extremely high volumes, around 85 to 95 decibels. For comparison purposes, 95 decibels is the equivalent of the noise of a subway train from 200 feet away. These loud, low sounds allow elephants to keep in touch with each other over distances of more than a mile. Listen to an example of these elephant rumbles from the Elephant Listening Project

See Also: 9 Strange Sounds No One Can Explain

[h/t: reddit

Scientists Capture the First Footage of an Anglerfish’s Parasitic Mating Ritual

The deep sea is full of alien-looking creatures, and the fanfin anglerfish is no exception. The toothy Caulophryne jordani, with its expandable stomach and glowing lure and fin rays, is notable not just for its weird looks, but also its odd mating method, which has been captured in the wild on video for the first time, as CNET and Science report.

If you saw a male anglerfish and a female anglerfish together, you would probably not recognize them as the same species. In fact, in the video below, you might not be able to find the male at all. The male anglerfish is lure-less and teeny-tiny (as much as 60 times smaller in length) compared to his lady love.

And he's kind of a deadbeat boyfriend. The male anglerfish attaches to the female's belly in a parasitic mating ritual that involves biting into her and latching on, fusing with her so that he can get his nutrients straight from her blood. He stays there for the rest of his fishy life, fertilizing her eggs and eventually becoming part of her body completely.

Observing an anglerfish in action, or really at all, is extremely difficult. There are only 14 dead specimens from this particular anglerfish species held at natural history museums throughout the world, and they are all female. Since anglerfish can't live in the lab, seeing them in their natural habitat is the only way to observe them. This video, shot in 2016 off the coast of Portugal by researchers with the Rebikoff-Niggeler Foundation, is only the third time we've been able to record deep-sea anglerfish behavior.

Take a look for yourself, and be grateful that your own relationship isn't quite so codependent.

[h/t CNET]

Cockroach DNA Shows Why They're Basically Indestructible

Most people are all too aware that cockroaches are horrifyingly resilient beings. Yes, they can and have survived nuclear blasts, and surely stand to inherit the Earth after we all succumb to the apocalypse. Why is this creature able to thrive in the face of pesticides, the loss of limbs, disgusting conditions, a range of climates, and even nuclear fallout, in urban kitchens across the world? As Inside Science reports, a new study on the genome of the American cockroach shows that certain genes are key to its wild evolutionary success.

In an article published in Nature Communications, researchers from South China Normal University in Guangzhou, China report that they sequenced and analyzed the genome of Periplaneta americana, and in the process they discovered just how indestructible this scourge is. They found that the cockroach (native to Africa, despite its American moniker) has more DNA than any other insect whose DNA has been sequenced except the migratory locust. The size of its genome—3.3 billion base pairs—is comparable to that of humans.

They have a huge number of gene families (several times the number other insects have) related to sensory reception, with 154 smell receptors and 522 taste receptors, including 329 taste receptors specifically related to bitter tastes. These extra smell and taste receptors may help cockroaches avoid toxic food (say, your household pesticide) and give them the ability to adapt to a multitude of different diets in different environments.

They also have killer immune systems able to withstand pathogens they might pick up from the rotting food they eat and the filth they like to live in. They have many more genes related to immunity compared to other insects.

The genome analysis might give us more than just a newfound respect for this revolting pest. The researchers hope to find a way to harness this new knowledge of cockroach immunity to control vermin populations—and create an eradication method slightly more effective than just stomping on them.

[h/t Inside Science]


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