When we think about hearing, it’s easy to assume that humans are the reference point. But our hearing is just one small slice of the sound spectrum. From ultrasonic squeaks to infrasonic rumbles, many animals experience a world of sound that’s completely hidden from us.
In this blog, we’ll explore the remarkable hearing abilities of animals, what that means for science and industry, and how technology helps us detect the sounds beyond human reach.
The Limits of Human Hearing
Most people can hear frequencies between 20 Hz and 20,000 Hz (20 kHz). That covers everything from the low rumble of thunder to the high-pitched chirp of a bird.
But our range is limited. As we age, our upper limit often drops, sometimes to below 15 kHz. That means many everyday high-frequency sounds, like the squeak of a mouse, become inaudible.
Ultrasonic Superpowers
Humans typically reach a frequency range of around 20 kHz, but many animals have evolved to detect frequencies far higher. These ultrasonic abilities aren’t just quirks of biology; they’re survival tools.
- Dogs (up to ~45 kHz): Dogs’ sensitive hearing allows them to pick up sounds that are completely inaudible to us. This is why dog whistles work: they emit high-pitched tones in the ultrasonic range. In the wild, this ability would help them hear prey moving through grass or communicate with their young at pitches predators couldn’t detect.
- Bats (20–120 kHz): Bats are the masters of ultrasound. By emitting rapid bursts of ultrasonic pulses and listening for the echoes that bounce back, they can “see” their environment through sound – a technique known as echolocation. This ability lets them catch tiny insects mid-flight, even in complete darkness, and navigate complex environments like caves and forests without hitting obstacles.
- Dolphins (up to 150 kHz): In water, where sound travels faster and farther than in air, dolphins use ultrasonic clicks and whistles both for communication and for hunting. Their echolocation is so precise that they can detect the difference between two objects the size of a marble. Ultrasound allows them to find fish hidden in sand or distinguish between friendly pods and rivals miles away.
For these species, ultrasonic hearing is as critical as sight is for us; without it, survival would be much harder.
Infrasonic Communication
At the opposite end of the spectrum are sounds that are too low for us to hear. Known as infrasound (below 20 Hz), these frequencies are often less about pinpoint precision and more about travelling incredible distances.
- Elephants (as low as 5 Hz): Elephants are famous for their deep, rumbling calls. These infrasonic signals can travel several kilometres, even through the ground, allowing herds to stay in contact across vast savannas. Scientists have observed elephants using infrasound to coordinate movements, signal danger, and even communicate courtship behaviour.
- Whales: Blue whales and fin whales produce some of the lowest-frequency sounds on Earth. Their infrasonic calls can carry across entire ocean basins, enabling communication with other whales hundreds, even thousands, of kilometres away. This is crucial for migration, breeding, and maintaining social bonds in the vast expanse of the sea.
- Giraffes and alligators: Once thought to be largely silent, giraffes actually produce low-frequency “hums” at night, which may help with group cohesion when visibility is poor. Alligators, meanwhile, generate powerful infrasonic bellows during mating season, causing water to visibly ripple as their bodies vibrate.
Unlike high-pitched ultrasound, infrasound is often more felt than heard, producing a physical sensation like a faint vibration in the chest. That makes it a powerful way to communicate over long distances or through dense environments like water, forests, or savannas.
The infographic below shows how different species compare to us:
Why This Matters to Us
Understanding animal hearing isn’t just fascinating trivia; it’s practical science:
- Engineering & Design: Learning from bats’ echolocation has inspired sonar and radar technologies.
- Environmental Science: Monitoring whales and elephants helps track migration, health, and even predict environmental threats.
- Workplace Safety: Some machinery produces ultrasonic or infrasonic noise that we can’t hear but can still have physical or psychological effects.
This is where precision instruments come in.
Measuring What We Can’t Hear
While our ears have limits, technology doesn’t have to. Sound level meters, dosimeters, and vibration monitors can capture frequencies outside human perception, helping us identify risks and understand complex environments.
At Cirrus Research, we design instruments that give you the full picture of noise exposure, whether it’s audible or hidden. By extending our “hearing” with the right tools, we can protect workers, safeguard communities, and even contribute to environmental research.
Animals remind us that sound is bigger than the human experience. From bats whispering in ultrasound to elephants rumbling in infrasound, the natural world is full of hidden voices.
With the right instruments, we can uncover those sounds, learn from them, and apply that knowledge to science, safety, and innovation.
