The inconsistencies of English spelling and the indeterminacies of its relationship to pronunciation mean that in English we frequently get the phenomenon of spelling pronunciation.
Spelling is, with rather few exceptions, fixed, while pronunciation varies. (That is why a high proportion of words in a pronunciation dictionary have more than one pronunciation shown.)
A speaker who is familiar with the written form of a word but not with its spoken form may, on the basis of the spelling, infer a pronunciation different from the traditional or generally used one. This is spelling pronunciation. Well-known examples include often with a t-sound and clothes with -ðz. In the case of backwards the spelling pronunciation with w has entirely displaced the earlier ˈbækədz, ˈbækɚdz. In the case of falcon, formerly ˈfɔːkən, my own pronunciation ˈfɔːlkən and the newer ˈfælkən represent successive stages of spelling pronunciation, as first the letter l and then the letter a receive their usual ‘value’.
There is an extensive discussion, with many other examples, here.
I particularly relish the Italian spelling pronunciation of Colgate toothpaste as kolˈɡaːte.
There are two related phenomena. One is pronunciation spelling, in which a new spelling is applied, reflecting the pronunciation better than the traditional spelling does. Popularly this is sometimes called phonetic spelling. An example would be the proper name Leicester ˈlestə, ˈlestɚ respelt as Lester. Another is though respelt as tho. Jack Windsor Lewis uses nonce respellings such as he’rd for heard and dou’t for doubt. Spelling reform projects typically involve systematic application of the principle of writing as we speak.
The other related phenomenon has no generally agreed name, but we could perhaps call it ’non-spelling pronunciation’. This is the adoption of a new pronunciation that does not match the traditional spelling. An example is the mɪsˈtʃiːviəs variant of mischievous that we discussed last week and that so upset the Daily Telegraph’s feature writer. Another is the widespread pronunciation of Westminster with -ˈmɪnɪstə instead of -ˈmɪnstə. Non-spelling pronunciation does particularly upset purists, and even from me tends to receive a warning triangle in LPD.
I suppose that if such pronunciations become established they are likely to lead to correspondingly changed spellings, thus mischievious and Westminister.
Non-spelling pronunciation followed by respelling is readily seen in the case of the word pronunciation, traditionally prəˌnʌnsiˈeɪʃn̩. Morphological regularization, ɡiven the base form pronounce prəˈnaʊns, produces prəˌnaʊnsiˈeɪʃn̩, which in turn gives rise to the unorthodox spelling pronounciation.
I have frequently had on-air conversations with radio presenters asking me about “pronounciation”, and I must confess that in reply I tend to pronounce pronunciation with extra clarity and care.