Your dog may understand more of your speech than you think. Have you ever talked to your dog and felt he was understanding every word? If your family and friends dismissed it, you might be heartened to know that scientific research could be backing you up. Research has shown that dogs may well not just be picking up on your tone of voice. They might be able to understand more than we previously thought. When we hear sounds, the right side of the brain processes tone of voice and the left side of the brain processes the content of speech. Our physiology means that the pathways between our right ear and the left side of the brain are stronger than from the left ear, and the pathways between our left ear and the right side of the brain are stronger. So we understand speech better from our right ear and the emotional tone of sound better from our left ear. Animals like dogs show a similar pattern when it comes to the sounds animals of their own species make. The question has always been: Do dogs make the same distinction when it comes to listening to human speech? A study by Victoria F Ratcliffe and David Reby which tried to answer that question was published in Current Biology (Orienting Asymmetries in Dogs’ Responses to Different Communicatory Components of Human Speech).The study positioned dogs between two speakers. Either a non-human or a human voice were played from both sides, simultaneously. The study looked at whether each dog turned its head to the left or right. That would indicate how the dog was processing the sound and which side it was hearing more clearly. The sound of the human voices used was enhanced to emphasise the faster-moving sound of the vocabulary, or modified to enhance the slower-moving sound of the emotional tone. The sound was varied between words and commands the dog was used to, and words in a foreign language were used. When the dogs were played the human voice speaking in a familiar language and with the vocabulary enhanced, most turned to the right. That showed the left sides of their brains were processing the words. When played the human voices in an unfamiliar language, most turned to the left, showing the right side of the brain was processing the sound. Most of the dogs also turned to the left when clips of human voices emphasising emotional tone, and removing the vocabulary, were played. The results indicated that to get a stronger reaction from the left side of the brain, there had to be meaningful verbal content. That's the same side of the brain which processes speech in humans. When there was no meaning to speech - where the language was unfamiliar or vocabulary removed - the right side of the brain took over in actively processing the sound. The team also played non-enhanced speech clips to the dogs. That normal speech prompted no such reaction, possibly because both components acted to cancel one another out when all the sound information was received at the same time. Overall, the study found dogs process sound in generally the same way we humans do. So how did this happen? Was it nature or nurture? Further research is now needed into whether this has always been inherent to dogs, or whether thousands of years of domestication by humans has created the situation. It's too early yet to say how much your dog understands, but the study showed he's not just responding to your tone of voice.