Imagine you’re drifting down the Kazinga Channel in Uganda. The sun is heavy. You see a pair of ears twitching above the water line, followed by a snout. Then, out of nowhere, the air literally shakes. It’s not a roar like a lion or a trumpeting blast like an elephant. It’s something weirder. It’s deep. It’s guttural. It honestly sounds like a giant, wet tuba player having a laughing fit. If you've ever wondered what noise do hippos make, you aren't alone; most people expect a quiet "water cow," but the reality is much more chaotic and loud.
Hippos are loud. Really loud. We’re talking 115 decibels. That is roughly the same volume as being in the front row of a rock concert or standing next to a jet taking off.
The Infamous Wheeze-Honk
The most iconic sound in the African bush—aside from maybe the hyena's whoop—is the hippo "wheeze-honk." Biologists call it that because it starts with a high-pitched inhalation and ends with a series of deep, resonant grunts. It sounds like HEEE-honk-honk-honk.
Why do they do it? It’s basically a roll call. Research led by Dr. Nicolas Mathevon at the University of Saint-Etienne in France has shown that hippos can actually recognize their friends' voices. They aren't just making noise for the sake of it. When a hippo lets out a wheeze-honk, it’s telling the rest of the pod—and any intruders—exactly who is there. In their study, published in Current Biology, researchers played recordings of hippos to different groups. The hippos reacted much more aggressively to the voices of strangers than to their own "neighbors."
They’re territorial. Extremely so. If a stranger "honks" in the wrong neighborhood, the resident bull might respond by spraying dung or initiating a physical confrontation. It’s a complex social language disguised as a series of goofy belches.
What Noise Do Hippos Make Under the Surface?
This is where it gets crazy. Hippos are "amphibious" in more ways than one, including how they talk. They are the only mammals that can send and receive vocalizations both above and below the water simultaneously.
They have this unique fatty tissue in their throats. It’s somewhat similar to the melon in a dolphin’s head. This fat helps conduct sound through the water. While their nostrils and ears are above the surface, they might be "clicking" or "clucking" underwater. If you were submerged with them (which, honestly, please never do), you’d hear a series of pulses and whirs.
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- Clicks: Short, sharp sounds used for short-range communication.
- Croaks: Longer, vibrating sounds that can travel miles through the water.
- Whines: High-pitched sounds often made by calves looking for their mothers.
Because water is denser than air, these sounds travel much faster and further. A hippo can essentially shout at a rival a mile down the river without ever popping its head up. This dual-channel communication is a massive evolutionary advantage. They can keep their eyes on the shoreline for predators like lions while coordinating with the pod beneath the surface.
The Grunt and the Chortle
Sometimes, the noise isn't a loud broadcast. It’s more of a domestic squabble. Hippos grunt when they’re moving through thick mud or adjusting their position in the pod. It’s a low-frequency sound. You can feel it in your chest before you hear it with your ears.
Calves have a totally different vocabulary. They don't honk. Not yet. They make a sound that is almost like a "moo," but shorter and more urgent. When a calf is separated from its mother in the murky water, it emits a high-frequency whine. The mother responds with a low-frequency rumble that the calf can feel through its skin. It’s an invisible tether.
Misconceptions About Hippo Silence
A lot of people think hippos are quiet because they spend 16 hours a day asleep in the water. Wrong. They are noisy sleepers. They puff, they snort, and they blow bubbles that sound like a bathtub draining.
People also mistake their "yawn" for a tired gesture. It’s not. When a hippo opens its mouth wide—showing off those massive, self-sharpening canines—it’s a silent threat. But it’s often accompanied by a "huff." This huff is a forced expulsion of air that signals "back off or things are going to get violent." It’s a precursor to the noise, a physical punctuation mark.
The Sound of Aggression vs. Play
How do you tell if a hippo is happy or about to charge? Context is everything.
Sub-adults engage in "jaw-wrestling." During these play fights, the noises are lighter. You’ll hear splashes and quick, repetitive grunts. It’s rhythmic. Contrast that with a territorial bull. His honk will be sustained. It will be followed by a "bellow"—a long, continuous roar that sounds surprisingly like a lion, but deeper.
When a hippo is truly angry, the noise stops being a "honk" and starts being a "scream." Yes, they can scream. It’s a terrifying, high-pitched sound that usually happens right before a charge. If you hear that, you’re already in trouble.
Why the Frequency Matters
Hippos utilize "infrasound." These are sounds at frequencies lower than the human ear can typically detect.
Elephants use this to communicate over dozens of miles. Hippos use it to keep the pod together in dense, silty rivers where visibility is near zero. Even if the water is too muddy to see your neighbor, you can "feel" their presence through the infrasonic rumbles they emit. This is why a pod of sixty hippos can move as one cohesive unit when a crocodile gets too close. They are literally vibrating together.
The Role of "Dung Showering"
Wait, why am I talking about poop in an article about noise? Because in the hippo world, they go together.
When a male hippo makes a loud wheeze-honk, he often simultaneously spins his tail like a propeller to spray dung. This is a multi-sensory "keep out" sign. The noise gets your attention, and the scent (and visual) finishes the job. It’s a very loud, very gross way of saying "This is my section of the river."
Scientific Studies on Hippo Vocals
For a long time, we didn't actually know that much about hippo sounds. They’re dangerous to study. You can't just put a microphone on a hippo’s collar.
However, in recent years, bioacousticians have used "hydrophones" (underwater microphones) to map out the riverbed soundscape. One study in the Kruger National Park found that hippos are most vocal at dawn and dusk. This coincides with their movement from the water to their grazing grounds on land. As they transition from their "water home" to their "land home," they are constantly checking in with each other.
The "honk" density increases significantly when the water levels drop during the dry season. Why? Because space is at a premium. When the river shrinks, the hippos are packed tighter, leading to more "arguments" and, consequently, more noise.
Common Questions About Hippo Sounds
Do they roar? Sort of. It’s more of a resonant bellow than a feline roar, but it carries the same weight.
Can they mimic other animals? No. Their vocal cords and the fatty tissue in their throats are specialized for low-frequency, high-volume honks and rumbles.
Are they louder than elephants? In terms of pure decibels, they are very close. An elephant's trumpet is sharper and travels further in open air, but a hippo's honk has more physical "oomph" in a river environment.
Do they make noise while eating? On land, they are surprisingly quiet. They spend the night grazing on grass, and since they are vulnerable on land, they tend to keep the "honking" to a minimum to avoid attracting lions. On land, you'll mostly hear the munch-munch-munch of them shearing grass with their tough lips.
Actionable Insights: What to Do if You Hear Them
If you find yourself near a waterway in sub-Saharan Africa, knowing these sounds isn't just a fun fact—it’s a safety requirement.
- Listen for the "Huff": If you are walking near a riverbank and hear a sharp Pshhh sound, stop. A hippo has seen you and is warning you. Do not get closer to take a photo.
- Identify the Wheeze-Honk: If you hear the HEEE-honk from around a bend in the river while in a boat, signal your guide. It means there’s a pod ahead, and you need to give them a wide berth.
- Vibrations in the Water: If you are in a small canoe and feel a low-frequency vibration through the floor of the boat, a hippo is likely vocalizing nearby underwater. Move toward the shore (carefully) and away from the deep channel.
- Respect the Night: If the "honking" gets louder and more frequent as the sun goes down, it’s a sign the hippos are preparing to leave the water. This is the most dangerous time to be on a hippos' "highway" (the paths they take to grazing lands).
Understanding hippo communication changes how you see these animals. They aren't just lazy giants. They are highly social, extremely vocal, and constantly "talking" in a language that spans both air and water. Their "honk" is a warning, a greeting, and a thumbprint all rolled into one. Next time you see a video of a hippo, turn the sound up. That goofy-sounding laugh is actually the sound of a 3,000-pound powerhouse claiming its kingdom.