I'm going to ask a very complicated question. The basic building blocks of LANGUAGE are phonemes, and according to research, sign systems have not been extremely successful at teaching our children the English language. With attempts to simcom, or speak and sign simultaneously, we attempt to show them some of the phonemes associated with each word. Is this beneficial? What about those that can't lip read?
It is not complicated: It is simple.
First you have to realize that you are looking at the tail of a snake and thinking it is the trunk of an elephant. It will never make sense until you realize you are asking and answering the wrong questions.
It is not according to research. It is ancient garbage posited by people before the study of linguistics, which is the study of language. They thought English and language were one and the same and they tried to make sense of English from the wrong end. Sort of like trying to understand water by starting with the equation H2O.
Phonemes are the building blocks of words -- Not language.
Hydrogen is one thing. Oxygen is another. They are not water until they come together in the right combination. And when you split them up they are no longer water.
The first building blocks of language are nouns. Those things we talk about. The first nouns are Mommy, Daddy, and MINE!
Next we work on the qualities of things and the relationships between them. Milk hot, water cold, dog bite. Mommy loves you.
It doesn't really matter whether the nouns are expressed as signs, written symbols, or spoken sounds. They are all models of the nouns they represent. You can make the sign of a whisker, the written symbol, show a picture, a hieroglyph, finger spell, or speak the word. A cat is a cat is a cat.
Where languages really diverge is in describing the relationships between nouns. Spanish and English handle indirect objects vastly different and ASL has the most straight forward approach.
Teaching phonemes to anyone, Deaf or hearing, can only have one purpose -- To help them master speech.
Who benefits from this? How? and Why?