Chapter 3. Classification of speech-sounds.

Speech-sounds are divided into vowels and consonants.
A vowel is a voiced sound produced in the mouth with no obstruction to the air stream.
The air stream is weak. The tongue and the vocal cords are tense.
A monophthong is a pure vowel sound. There are 10 of them:[i],[e],[æ],[a],[υ],[Λ],[ə],[a:],[Ɔ:],[ʒ:].
A diththong is a complex sound consisting of two vowel elements but pronounced as a single syllable.
In the pronunciation of a diphthong the organs of speech start in the position of one vowel and glide in the direction to the another vowel
The first element of an English diphthong is called the nucleus. It is strong, clear and distinct.
The second element is rather weak. It is called the glide.
There are 8 diphthongs – three with a glide [i] – [ei] [ai] [oi]
                                        two   with a glide [u] -[au] [ou]
                                        three with a glide [ə] -[iə] [εə] [uə]
There are two vowels [i:],[u:] which may have a diphthongal pronunciation but very slightly.
You know that the consonants are divided into voiced and voiceless according to the work of the vocal cords.