5 Things You Never Knew About the Human Voice

Your Accent Is Formed in the Womb

Before birth, humans spend months listening to sounds — including voices — from inside the womb. The ability to hear begins around 18 weeks gestation, and by the third trimester fetuses respond to the sound of their mothers’ voices with slower heart rates and reduced movement. Studies have shown that newborns recognize and prefer their mothers’ voices from the moment they’re born. 

In the womb, babies also listen to the patterns of what will become their native tongue. Incredibly, there’s even evidence that language development starts before birth. A study of newborns in Europe found that French babies’ cries more often followed a rising melody, with higher frequencies as the cries progressed, while those of German babies had a falling melody. This corresponds with the pattern of those languages, as French words and phrases tend to have a rising pitch and German more often has a falling pitch at the end of a word or phrase.

Each Voice Is Unique

The way your voice sounds is determined by the shape and size of your vocal cords, the volume of air your lungs can contain, the ways you use your mouth and tongue to form sounds, and more. All those factors are highly specific to each individual, combining to make our voices unique identifiers much like our fingerprints. One statistical review determined that the chances of two humans having identical vocal patterns was at most one in a few thousand and could be up to one in a septillion.

Some Humans Can Make Sounds We Can’t Hear

Sound frequency — how “low” or “high” in pitch a sound seems to us — is measured in hertz, a unit of cycles (in this case, sound waves) per second. In general, humans can hear a range from roughly 20 hertz to 20,000 hertz, although that varies between individuals and across a person’s lifespan.

The voice, however, has been found to extend beyond this range. Using special frequency detecting equipment, Guinness World Records confirmed that the lowest note ever sung, achieved by American singer Tim Storms in 2012, was only 0.189 hertz, well below the range of human hearing. On the other end of the spectrum, the highest note ever measured, sung by Brazilian singer Georgia Brown, hit about 25,000 hertz, well above the top of our normal hearing range.

Human Voices Can Be So Loud It’s Painful

Like pitch, volume is determined by sound waves, or more specifically, how “big” the waves are — aka their amplitude, which is measured in decibels. A quiet sound, such as a human whisper, is about 20 to 30 decibels, while normal conversation is about 60 to 70 decibels. Sustained exposure to more than about 90 decibels may result in hearing loss, and anything over 125 decibels starts to cause pain to the listener.

It may surprise you that some of the loudest humans ever recorded have even exceeded that pain threshold. In 2000, a teaching assistant from the U.K. named Jill Drake was recorded shouting at 129 decibels. That’s louder than a power saw or a rock concert and nearly the level of a jet engine!

Animals Are More Scared of Human Voices Than Lion Calls 

The African Savanna can be a dangerous place for many animals, as predators lurk in the grasses at every turn. Lions, the longtime undisputed kings and queens of the wild, are some of the most fearsome. And yet, the sound of another animal — human beings — strikes even more fear into the hearts of some prey.

Researchers in South Africa’s Kruger National Park played recordings of human conversation, dogs barking, gunshots, and lion growls and snarls through loudspeakers at watering holes in the park. They found that 95% of the animal species who heard the recordings were more likely to flee when they heard the human voices — including zebras, warthogs, impalas, rhinos, and leopards. Elephants were the only species significantly more likely to run away from the lion sounds.