phonology

      Phonology is the study of how sounds are organized and used in natural languages or it is essential the description of the system and patterns of speech sounds in a language. Based on theory of what every speaker of a language unconsciously knows about the sound of patterns of the language. so, phonology is concerned with the abstract or mental aspect of the sounds in language rather than with the actual physcal articulation of speech sounds.

     phonology is about the underlying design, the blueprint of each sound , which serves as the constant basis of all the varitions in different physcal articulations of that sound type in different contexts. When we think of the [t] sound for examples,tar, star, writer, and eighth as being the same. they would be represented in the same way. but it is not, [t] sounds are all different. however in different [t] sounds are less important to us than the distinction between of [k], [f], [b] sounds, because there are meaningful consequences related to use of one rather than the others.

     Phonemics is a particular set of sounds produced in a particular language and distinguishable by native speakers of that language from other (sets of) sounds in that language. That's what "distinctive" means -- the English phonemes /n/ and /ŋ/ can be told apart by native speakers of English, because we use these sounds to distinguish different words -- sin ~ sing, ton ~ tongue, run ~ rung, etc. This would be impossible if these phonemes weren't distinctive in English.

      when we learn to use alphabatic writting, we are actually using the concept of the phonome as the single stable sound type which is represented by a single written symbol. It is in the sense that the phoneme /t/ is described as a sound type, of which all the different spoken version of [t] are token. An essential property of a phoneme is that it functions contrastively. We know there are two phonomes /f/ and /v/ in english because there are the only basis of contrast in meaning between the words fat and vat or fine and vine. This contrastive property is the basic operational test for determining the phonemes that exist in a language. If we substitute one sound for another in a word and there is a change of meaning, then the two sounds represent different phonemes. The basic phonemes of English are listed with the consonant, vowel and diphthong diagrams in 

 Phones & Allophones 

      The vowels in the English words "cool", "whose" and "moon" are all similar but slightly different. They are three variants or allophones of the /u/ phoneme. The different variants are dependent on the different contexts in which they occur. Likewise, the consonant phoneme /k/ has different variant pronunciations in different contexts. Compare:

     Phones are phonetic units and appear in square brackets. When we have a set of phones, all of which are versions of one phoneme, we add the prefix “allo-” (= one of a closely related set) and refer to them as allophones of that phoneme. Phones are phonetic units and appear in square brackets. When we have a set of phones, all of which are versions of one phoneme, we add the prefix “allo-” (= one of a closely related set) and refer to them as allophones of that phoneme.