Do dogs of all ages respond equally to dog-directed speech?

When talking to dogs, human adults use pet-directed speech similar to infant-directed speech (high pitch, slow tempo), which is known to engage infant attention and promote language learning. What about our dog companions? An international research team, led by Dr. Nicolas Mathevon of Hunter College, City University of New York (CUNY), and the University of Lyon/Saint-Etienne, has demonstrated that puppies are highly reactive to dog-directed speech but that older dogs do not react differentially to dog-directed speech compared to normal speech. Yet, human speakers employ dog-directed speech with dogs of all ages, suggesting that this register of speech is used to engage interaction with a non-speaking, rather than just a juvenile, listener.

Not only might people consciously or unconsciously wish to make themselves better understood through dog-directed speech, they may also be promoting word learning in dogs when doing so. It remains an open question whether puppies react innately to dog-directed speech and exactly why adult dogs showed a lack of preferential reactivity (at least in the absence of other communication cues) to dog-directed speech.

For now, people seem to consider dogs non-verbal companions and speak to them as they would human infants. We use similar strategies in other situations where we believe our listener may not fully understand us, such as when speaking to elderly people or linguistic foreigners.