Curious kids: How far away can dogs smell and hear?

How far away can dogs smell and hear? Georgina, age 8, Warrawee, New South Wales.

Great question Georgina. We know and learn about the world around us through our senses. The senses of smell and hearing in dogs mean they experience a different world to us.

Dogs have many more smell receptors than humans – a receptor is a part of the nose that recognises each unique smell particle.

Dogs also have a lot more surface area in their noses and are better at moving air through their noses than us. Watch a dog sniffing and you can see this for yourself. If more air passes through their nose they have more chance to pick up smells.

How far dogs can smell depends on many things, such as the wind and the type of scent. Under perfect conditions, they have been reported to smell objects or people as far as 20km away.

Read more: Curious Kids: why might you wake up without a voice?

You might be interested to know dogs are not the only great smellers. The scientific family dogs belong to is Carnivora. This includes cats, bears and skunks.

These animals have incredible senses of smell as well. Bears have some of the best senses of smell in the family. Polar bears can smell seals, which they hunt, from more than 30km away.

How would it feel if you knew just by smell when your best friend was in the next room, even if you couldn’t see them? Wouldn’t you love to know where your parents had hidden your favourite chocolate biscuits in the pantry, just by sniffing them out?

Dog the detector

This amazing sense of smell means dogs have some of the most interesting jobs of any animal: the detection dog.

Detection dogs help search and rescue organisations to find missing people, look for dangerous materials such as drugs and bombs, illegal imports at airports, and help find wild animals.

All of it’s done with their noses, which makes dogs some of the best sniffers in the world.

Even pet dogs enjoy playing games using smell.

Read more: Curious Kids: Why is our dog so cute?

One thing that might still puzzle you is why, when dogs have such a great sense of smell, they like to smell things that are disgusting to us, like other dogs’ bottoms. That’s a story for another day.

Hear and far

Now we know dogs can smell lots of things from far away, what about their hearing? What can dogs hear, and from how far? To find out, first we have to talk about what dogs and all animals (including us) hear: sound frequencies.

Sounds have waves. The frequency of sound is how close together the sound waves are. The closer together the waves, the higher the frequency or pitch. You can think of this like the beach during a storm, when waves hit the beach more often.

Dogs and people hear about the same at low frequencies of sound (around 20Hz). This changes at high frequencies of sound, where dogs hear up to 70-100kHz, much better than people at only 20kHz. Dogs hear sound frequencies at least three times as high compared to people.

You may have wondered how those special silent dog whistles work? They make high-frequency sounds that dogs can hear but we can’t. Because dogs can hear higher frequencies than us, there are a lot more sounds for dogs to hear.

They can also hear sounds that are softer or farther away, as far as a kilometre. That means dogs can be more sensitive to loud sounds. This is why some dogs are scared of fireworks or thunderstorms. It is also why a dog might bark at a sound you cannot hear.

Prick up your ears

Part of how dogs hear so well has to do with their ear muscles. Dogs have more than a dozen muscles that allow them to tilt, lift and rotate each ear independently of one another.

This helps dogs locate where sounds come from. It is also part of why dogs may tilt their heads to some sounds. Police who use dogs say the first sign their dog has located a suspect is when they see their ears move around to focus on a place.

Having great hearing also helps dogs with another one of their interesting jobs: the assistance dog. Assistance dogs work with people who need help in their daily lives, such as those who are blind or deaf.

Read more: Why dogs don’t care for being groomed (and for the love of dog don’t snip their whiskers)

Excellent hearing means dogs can identify people arriving at a home or oncoming traffic at a walkway. With such great hearing, dogs can help people in need navigate the world around them too!

Thinking about different senses is a great way to learn about all animals. What are their senses like? How does that help them think about the world differently to us?

This was a fantastic question, Georgina, and we hope you enjoyed these answers as much as we enjoyed answering them.

Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to curiouskids@theconversation.edu.au