Why don't dogs get hoarse when they bark a lot?

It seems like some dogs can bark and bark for hours. Yet they never seem to get hoarse or lose their voice (bark) like people do when they talk, yell, or sing too much. Veterinarians (animal doctors) think that is because a dog’s voice box, or larynx, is not as complicated as the larynx of a human, who needs to make a wide range of different sounds to speak. So the stress that results from excessive barking doesn’t do nearly as much damage as overusing a human voice does.