The Basics of Canine Communication 

We know a dog cannot understand words or sentences as we understand them. They have no comprehension of the human language; they are conditioned to respond to sounds in a specific way. It really doesn't matter which word the trainer uses for a command, just as long as the chosen word is short and unique in its sound. Which brings us to how the word is said or the sound of the command. If you teach the dog to respond to a long tone si- i- i- it, and then you tell him sit in a short tone, your dog will get confused and probably experiment with different behaviors until he finds one that works. They might guess right the first time, but they would still be guessing, not responding with confidence. So once you figure out how you're going to say the commands, you need to say them the same way consistently.

Dogs understand body language, they must learn our words.

Often our body language says something different to the dog than what our words are saying. Dogs will normally follow the body language command first.

Remember to be consistant with both your body language and your verbal command.