Teaching your dog to "Speak"

Step 1: put your dog in front of you and tie him to something that won't move. Make sure he is comfortable.

Step 2: Have a few treats in your hand and show the dog and let him smell them in your hand.

Step 3: Slowly, while making eye contact with you dog, move away a few feet. The key here is to tease you dog... make him want the treats really really bad. Don't say anything this entire time. Maybe move towards and away from your dog a few more times never making contact with him.

Step 4: VERY IMPORTANT... As soon as your dog makes any noise, go and pet him and give him a treat. This could be a whimper, a faint bark, or a grunt.

Step 5: Start over again after you have praised your dog and start teasing him again and each time he makes a noise praise and give him a treat.

Step 6: Once your dog is starting to figure out what you want, look for signs that he is going to bark and say "Speak" only once and then praise when he barks or makes a noise. It helps to add a hand signal to this like opening a closing your fingers like a mouth.

WIth repetition you will have a dog that speaks on command.
If you dog is making some sort of noise almost every time but isn't actually barking try waiting a little longer and seeing if he will keep making noise before praising.
Once dogs figure it out they usually become pretty confident in themselves. And believe it or not, a dog that knows the speak command will be easier to teach to be quiet when you have an unwanted barker.