Phonological variation *
The principle of “one letter—–one sound” introduced in the introduction of this chapter explains why Turkish writing is based on a phonological alphabet, and that such a system takes no account of a pronunciation that deviates from the spelling. For free or predictable variation rules can be set up describing the circumstances under which such variation occurs. Besides vowel reduction (stress induced) and differences in vowel quality (vowel length), phenomena such as contraction in rapid speech are discussed, as well as expansion—the way in which foreign words are adapted to the Turkish sound system and included in the vocabulary. The fully predictable effects of front and back vowels on the quality of certain consonants and other types of assimilation are treated in the final sections.