In most languages, the letters of the alphabet used for spelling do not always correspond exactly to the actual speech sounds. This is especially true for English, as you are well aware, and some of your difficulties with English pronunciation are most likely a direct result of this fact. Let us consider a few examples of the discrepancies between spelling and pronunciation:
1) often words have more letters than sounds as in the word “shoe” which has four letters but only two sounds;
2) the letter may have no relation to the sound as in the word “phone” which is pronounced as “fone”, or the word “of” pronounced as “ov”;
3) words may be spelled differently but pronounced the same as with the words, “to, too, two”;
4) words may be spelled the same but pronounced differently as with the verb “use”, pronounced as “uze” and the noun “use”, pronounced as “use”;
5) different letters may be used for the same sound such as the words “keep” and “cook” in which the beginning letters “k” and “c” are both pronounced as “k”;
6) some letters may be silent such as the letter “b” in the word “thumb”, the letter “k” in the words “know”, and the letter “t” in the word “listen”. These are only a few examples of the limitations of English spelling, and you will probably think of many more from your own personal experience.
Because of the inherent ambiguity in attempting to discuss the sounds of English using the conventional alphabet and spelling system, it is helpful, if not necessary, to use phonetic symbols. The symbols used to discuss sounds are typically adopted from the International Phonetic Alphabet, or IPA. The IPA is the system commonly used for research and language teaching purposes and includes symbols for most of the sounds of the World’s languages.