I think one of the most difficult issues in training our children is to teach them to be quiet. For some it comes easily right from the start, while others have so much to say and with such great volume! Here are a few tips:
-Teaching little ones some basic sign language – before they are able to talk is very helpful. To begin with, it gives them the ability to communicate some basic desires. In addition, it provides an action for them on which to focus. For instance, I remember numerous meals when the baby in highchair would loose control. Simply asking him to quiet down was ineffective. If in addition, we required a response in the form a hand motion saying, “Yes,” the crying usually would stop. The process included gently taking the child’s hand to help him learn to make the motion. Not only encouraging the the habit of responding when spoken to, it also distracts the child, helping him to stop crying. These three are what we used most; YES, PLEASE, and THANK YOU.
“Yes”
“Please”
“Thank you”
(photos from BabySignLanguage.com)
-These responses should be continued to be required as the child grows. An appropriate response of “Yes, Ma’am/Sir” or “Yes, Mommy/Daddy” confirms that the child heard you and instills respect.
-Eye contact is extremely important. In a busy household, it is easy to throw out a request, “Quiet down!” and never even look at the child. The child may or may not even notice that you said anything. I learned that if I made the request once (ONLY ONCE) in a quiet voice and looked directly at the child and held the gaze until they obeyed, the outcome changed dramatically! We should not have to shout, repeat, count…
– In an effort to teach her youngest the quiet concept, my niece wisely created a LOUD/ quiet game. It is a great way to have fun teaching littles ones how to whisper. It could be as simple as playing “Simon Says”, acting like loud monkeys / quiet bunnies or practicing musical dynamics with Piano/ Forte. The important thing is to be creative and practice, practice, practice!
-Be consistent. These are concepts that don’t happen overnight. Have fun and laugh over the mistakes.
Not Without Aim 
: )