How many kilometer does the dog can hear?

Dogs can't "hear" kilometers. Kilometers are a unit of distance, not sound.

Dogs have excellent hearing, much better than humans. They can hear sounds at much higher frequencies and lower volumes than we can.

To answer your question in a way that makes sense, let's rephrase it:

How far away can a dog hear a sound?

The answer depends on many factors:

* The type of sound: Some sounds, like high-pitched whistles, travel further than low-frequency sounds.

* The environment: Noise and other factors can interfere with sound travel.

* The dog's breed: Some breeds have naturally better hearing than others.

Generally, dogs can hear sounds up to 4 times further away than humans. This means a dog might be able to hear a sound up to 1 kilometer away, while a human might only hear it at 250 meters.