Mine learn by hand signal first, it's easier for them to learn. Then I switch to voice commands. Give the voice command, then follow immediately with the hand signal for three sessions. then, delay the hand signal two seconds for three sessions, then 4 seconds, then, only as a reminder if the dog looks puzzled. Inside a month, no need for hand signals, the word is enough. Be careful to use the same tone of voice at first, then begin changing it up after the dog responds to voice alone, finally have others command the dog but, be there to show the hand signal until the dog learns the word in any tone and given by male, female, adult and, child. Takes me about six months to get a dog responding to six voice commands by anyone in my home.