L.S.
I always told my children that I couldn't understand them if they were whining for example if my daughter said " I want you to read me a book" in a whiny voice I would tell her "I'm sorry, I can't understand you when you whine" if she kept saying it in a whiny voice I would just ignore her and then she would say it in a nice voice and I would turn and answer her and say "good, now I can understand you". It seemed to work in my house but I always said first that I couldn't understand them because they're whining so they would know why I was ignoring them if they continued...Good luck