We have our own secretive language with our pups, but there's actually an ideal way to communicate with them!
This communication starts from the time that your dogs are puppies. If you're raising a puppy, there's a specific way you can talk to them to help their training stick. The goal should be to speak with "dog-directed speech," which means changing the way that we speak in terms of the length of sentences and the vocabulary used.
There are many studies on "baby voices" and how these connect to our "dog voices" or "puppy voices." Past studies have suggested that the voices we use to talk to puppies is actually even higher-pitched than the voices we use to talk to babies - and this is a good thing! These studies have also shown that dogs (puppies, especially) best respond to higher pitches, since this often indicates excitement.
While dogs can't understand English, they do understand when you're attempting to communicate with them. This is shown in studies where owners point to a cup and make eye contact with their dog, typically leading to the dog nudging the cup to see what's underneath.
These visual communication skills can also crossover to speech. Your voice and tone can help tell a dog how they should react or what they should do. That's why your tone and inflection matters!
To communicate best with your dog, establish a consistent and clear vocabulary. This is achieved through clear commands like "sit" and "stay," or just repeated phrases like "good girl," and "great job." Using a limited vocabulary with your dog and keeping your phrases and words short will help your dog understand that you're communicating with them, and what you're communicating. Be sure to use inflections, too! Establishing inflections with your pup early on will help them know when you're upset and when you're happy.
And of course, use your hands! While you can often communicate by talking to your dog, your pup can best understand you when you're using visual cues, as well!