I have owned a variety of dogs since I was five years old, and some seemed to be talking to me. My standard poodle, Lady, was the smartest, but she understood what I told her, but was not very expressively communicative. Buster, my most recent pet, a Shih Tsu, who sadly left me almost two years ago at 17 years of age, seemed to have the most to say, but I didn't understand him.
Gayle Ehlman has described how to interpret your pets growls and body language but Takara Tomy, a Japanese toymaker, has made a device that can translate what a dog "says" into human language and emotions in real time. Go to their website and read "how they developed with an acoustics research laboratory and a veterinarian, the Bowlingual" which works wirelessly (your dog must wear a wireless mic around the neck). Let the device catch noises made by your dog (transmission range: 10m) and it will analyze the "animal language" with a special algorithm before telling you on the LCD screen what was being "said. (Cat lovers should know that Takara Tomy has also released the Meowlingual Cat Translator.)
Since Buster was always with us, whether in the bath room or bedroom, I might insist that he sign a non disclosure agreement before fitting him with the Bowlingual. However, the Bowlingual device is probably more of a novelty than an accurate translator and reviews of the device showed that it didn't work too well....at least with non-Japanese speaking dogs. It does seems to work OK with dogs and British men in Japan. The Bowlingual device is difficult to find in retail stores int he U.S., but there seem to be a lot of units for sale on Ebay.