H.B.
I actually had a pair of ear plugs, the huge kind you'd use at a gun range--but earmuffs would work to. Whenever my daughter would whine, I'd tell her I was going to have to put on my "Whine Mufflers" and as soon as they were on I would not be able to hear her until she spoke using a regular tone of voice. Then I would proceed to go about my work and completely ignore her. Her whining and crying would increase at first because this really frustrated her. And of course I could really still hear her, but she didn't know that.
The minute she started speaking in a regular tone of voice, I would look at her and remove the earplugs saying, "oh, you must be speaking normally because I can hear you now."
This worked great!