"The unlucky thing for English spelling is that during the very same time, huge changes in pronunciation were happening. Middle English was becoming Modern English. ... So we get one spelling for many vowel sounds—ea in knead, bread, wear, and great—and multiple spellings for one vowel sound—due and dew, so and sew." - Google says it..
I was searching the topic and found this short crispy answer in Google.
Thanks for sharing good stuff Leo. The Synergy method you have mentioned is for balancing a language, that is really helpful. But one has to focus properly from the very beginning of learning a language. Though the concept of Phonetics comes later and that's an important part of Linguistics, still it's always better to have knowledge of Phonemes. From that originates actual pronunciation. Each and every alphabet has an in depth conceptual phoneme as well as pronunciation. Then comes spellings. Think of the Language studies, go into core as much as possible, live with Language, I always advise my well known s who are obsessed with language learning.