When we talk to dogs, they hear our words. However, our tone of voice speaks even louder.
For the past several years, I have been walking Client X. We get along fine. Client X is a self confident, reasonably intelligent dog. He enjoys chasing Robins, smelling things, and finding large sticks which he then carries home to add to his collection (kept in an unruly pile just outside the backdoor).
The other day after we finished our walk, Client X stood at the entrance of his kitchen while I stood on the landing. As I removed his leash, I knocked over my bag. The bag tumbled down the basement stairs spilling its contents. While I picked up the poop bags and business cards and extra leash and collar and lip balm and assorted other workday necessities that sprayed out of the bag, I released a series of animated curses and sundry cussing style vocalizations.
When I returned to Client X, he was cringing. I had never seen him cringe before. But then, I'd never before had a hissy fit in his presence.
The reaction of Client X is a good reminder that dogs do listen to us. When we want them to obey a command, we use our authoritative voice. When we want them to lick our face, we pull out the sing song voice. When we yell expletives, they cringe - even if we don't want them to.