through the nasal cavity The larynx contains the vocal cords, which can be brought near together When they are drawn near together, they are made to vibrate by the air coming from the lungs, thus producing voice The lips, the tongue, the soft palate with the uvula, the vocal cords and the lower jaw are very active in the articulation of speech sounds. So speech sounds are produced by the vibration of the vocal cords and the definite movement of these organs of speech Part 3 The classification ofspeech sounds The organs of speech are capable of making many different kinds of speech sounds. From the practical standpoint, speech sounds are generally divided into Vowels and Consonants Vowels are sounds produced without obstruction of the air stream in the mouth In producing them there is vibration of the vocal cords, so all vowels are vo iced In English there are twenty vowels in all Consonants are sounds produced by some form of obstruction of the air passage and be either voiced or voiceless. There are twenty-eight consonants in English The english vowels The English vowels are divided into two large groups: Monophthongs and Diphthongs. Monophthongs are simply vowel sounds. When we utter a Monophthongs the jaw, tongue and lips do not move while it is being uttered. The diphthongs is a glide from one vowel to another within one sy llable. When we utter a Diphthongs the jaw, tongue and lips must move from one position to another. It is be classified accord ing to the following principles. elve monop important t to observe this difference. There are twelve monophthongs. They may 1)The height of the raised part of the tongue: we distinguish open vowels, half-open vowels half-close vowels and close vowels 2)The part of the tongue raised: we distinguish front, back and central vowels 3) The length of the vowel: we distinguish long vowels and short ones 4)The position(or shape )of the lips: we distinguish rounded vowels and unrounded nes 5)The degree of tenseness: we distinguish tense vowels and lax vowels Monophthongs(单元音) The frontⅤ owls 1)Common features 1)the front of the tongue is raised to various levels in the direction of the hardthrough the nasal cavity. The larynx contains the vocal cords, which can be brought near together. When they are drawn near together, they are made to vibrate by the air coming from the lungs, thus producing voice. The lips, the tongue, the soft palate with the uvula, the vocal cords and the lower jaw are very active in the articulation of speech sounds. So speech sounds are produced by the vibration of the vocal cords and the definite movement of these organs of speech Part 3 The classification of Speech sounds The organs of speech are capable of making many different kinds of speech sounds. From the practical standpoint, speech sounds are generally divided into Vowels and Consonants. Vowels are sounds produced without obstruction of the air stream in the mouth. In producing them there is vibration of the vocal cords, so all vowels are voiced. In English there are twenty vowels in all. Consonants are sounds produced by some form of obstruction of the air passage and be either voiced or voiceless. There are twenty-eight consonants in English. The English vowels The English vowels are divided into two large groups: Monophthongs and Diphthongs. Monophthongs are simply vowel sounds. When we utter a Monophthongs the jaw, tongue and lips do not move while it is being uttered. The diphthongs is a glide from one vowel to another within one syllable. When we utter a Diphthongs the jaw, tongue and lips must move from one position to another. It is important t to observe this difference. There are twelve monophthongs. They may be classified according to the following principles: 1) The height of the raised part of the tongue: we distinguish open vowels, half-open vowels, half-close vowels and close vowels. 2) The part of the tongue raised : we distinguish front, back and central vowels. 3) The length of the vowel: we distinguish long vowels and short ones. 4) The position (or shape) of the lips: we distinguish rounded vowels and unrounded ones. 5) The degree of tenseness: we distinguish tense vowels and lax vowels Monophthongs （单元音） The Front Vowels 1) Common features : 1) the front of the tongue is raised to various levels in the direction of the hard