Maltese deafness

My maltese has been deaf since birth (she is now 6 yrs old). I did not find this out until I took her to puppy school and she did everything but respond to her name. She has done very well, she is intelligent and has picked up hand signals very well. However, I have trouble communicating to her that she must not bark. As a rule, she is not a barker, but at times I wish I could get that message across. Does anyone out there know of maltese deafness, or what causes it? I would like to hear from other deaf dog owners on what they have done.