THE ORGANS OF SPEECH AND THE FORMATION OF SOUNDS. CLASSIFICATION OF ENGLISH SPEECH SOUNDS

1. The organs of speech and formation of sounds

A. Speech organs (articulators) - all the sounds we make when we speak are the result of muscles contracting. 
The muscles in the chest that we use for breathing produce the flow of air that is needed for almost all speech sounds. Muscles in the larynx produce many different modifications in the flow of air from the chest to the mouth. After passing through the larynx, the air goes through what we call the vocal tract, which ends at the mouth and nostrils. Here the air from the lungs escapes into the atmosphere. We have a large and complex set of muscles that can produce changes in the shape of the vocal tract, and in order to learn how the sounds of speech are produced it is necessary to become familiar with the different parts of the vocal tract. These different parts are called articulators, and the study of them is called aticulatory phonetics. Articulators produce the sounds of language. Organs used include the lips, teeth, tongue, alveolar ridge, hard palate, velum (soft palate), uvula and glottis.

RESONANT SOUNDS. VOWELS

1. Resonant sounds 

A. Definition of resonant sounds - in phonetics and phonology, a sonorant or resonant is a speech sound that is produced with continuous, non-turbulent airflow in the vocal tract (a sound produced with the vocal cords so positioned that spontaneous voicing is possible); these are the manners of articulation that are most often voiced in the world's languages. Vowels are sonorants, as are consonants like /m/ and /l/: approximants, nasals, flaps or taps, and most trills (a vowel, a glide, or a liquid or nasal consonant).

In older usage, only the term resonant was used with this meaning, and sonorant was a narrower term, referring to all resonants except vowels and semivowels.

COMPLEX VOWELS AND VOWEL COMPLEXES: DIPHTHONGS AND TRIPHTHONGS

1. Diphthongs

A. Definition - a diphthong  (Greek: diphthongos, literally "two sounds" or "two tones"), also known as a gliding vowel, refers to two adjacent vowel sounds occurring within the same syllable. Diphthong is a sound which consist of a movement or glide from one vowel to another. A vowel which remains constant and does not glide is called a pure vowel, and one of the most common pronunciation mistakes that result in a learner of English having a "foreign" accent is the production of pure vowels where a diphthong should be pronounced.
Technically, a diphthong is a vowel with two different targets: that is, the tongue (and/or other parts of the speech apparatus) moves during the pronunciation of the vowel.
Perhaps the most important thing to remember about all the diphthongs is that the first part is much longer and stronger than the second part