• Phonetics is the study of human sounds and phonology is the classification of the sounds within the system of a particular language or languages.
• Phonetics is divided into three types according to the production (articulatory), transmission (acoustic) and perception (auditive) of sounds.
• Three categories of sounds must be recognised at the outset: phones (human sounds), phonemes (units which distinguish meaning in a language), allophones (non-distinctive units).
• Sounds can be divided into consonants and vowels. The former can be characterised according to 1) place, 2) manner of articulation and 3) voice (voiceless or voiced). For vowels one uses a coordinate system called a vowel quandrangle within which actual vowel values are located.
• Phonotactics deals with the combinations of sounds possible and where sounds can occur in a syllable.
• The major structure for the organisation of sounds is the syllable. It consists of an onset (beginning), a rhyme (everything after the beginning) which can be sub-divided into a nucleus (vowel or vowel-like centre) and a coda (right-edge).
• The unstressed syllables of English show characteristic phonetic reduction and words containing this are called weak forms.
• It is essential to distinguish between writing and sound. There are various terms (homophony, homography, homonymy) to characterise the relationship between the written and the spoken form of words depending on what the match between the two is like.
Cardinal Vowels
Note The left symbol of each is unrounded; the right one is rounded. There is a general correlation between unroundedness and frontness and roundedness and backness, i.e. these value combinations are much more common than their opposites.
Alphabet systems
• A different principle is used in languages which use characters (such as Chinese). In these cases a symbol stands for an entire word or at least for a syllable. Such languages have a very large number of symbols, as in principle there is one per word, though by means of repetition and combination the number required can be reduced.
• Alphabet systems are the most economical and can do with sets of symbols consisting of about 30 (26 letters in English, for instance). Alphabet systems are a development from older pictographic systems in which stylised abstractions were used in writing, e.g. a circle for the sun, a vertical stroke for a man, etc.
• The letters of an alphabet may have their own names as with the Runic alphabet (early Germanic system in the first centuries after Christ). The forms of letters may vary with no effect on their sound values, e.g. letters may appear in italics or bold or UPPERCASE.
In order to characterise vowels satisfactorily the cardinal vowel system was introduced at the beginning of the 20th century by the English phonetician Daniel Jones. The basic principle is that extreme positions for the articulation of vowels are taken as reference points and all other possible vowel articulations are set in relation to them.
The vowel quadrangle used for the representation of vowels is derived from a side view of the oral cavity with the face turned to the left, that is the position of /i/ is maximally high and front, the position of /u/ is maximally high and back while the low vowels /a/ and /ɑ/ are maximal low front and low back respectively. 
The following charts are given for the sounds of English; note that the values refer to Received Pronunciation and vary greatly between varieties of English. 
