Why do dogs wake up with just a small sound?
They always stay alert, even when they sleep. They are originating from wild animals and in the wilderness it's better to wake up before you get eaten.
I've never noticed that before..........
because they have sensitive hearing
I can to that. I was in Washington and my friends phone was on vibrate..it vibrated and I was UP
Some animals such as dogs have better hearing then humans do.
The reason dogs wake up to a small sound is because they have very strong hearing and they want to keep there owners safe.
Dogs can hear infrasound sound that is the reason they wake up with a such a low intensity sound which the normal human ear can not detect :D
Most animals don't sleep for long, they grab 15 minutes here and there and take naps, but they stay awake like that to survive.