The study of speech sounds which are utilized by all human languages to represent is called phonetics which is concerned with describing speech sounds that occur in the language of the world.
So the first job of the phoneticians is trying to find out what people are doing while talking as well as listening to the speech.
Aspect
Articulatory phonetics: The study how the vocal tract produces the sound of language. First of all, the air-stream provided by the lungs undergoes important modification in the upper stages of the respiratory tract before it acquires the quality of a speech sound.
In the larynx, with the action of the vocal cords that the sound can be found voiced ( b, d, m …) or voiceless ( p, t, k…). After the larynx, the air-stream is subjected to the further modification as being released, according to the position of the soft palate that result in nasal sounds, (m, n, ŋ) If the nasal sound cavity is used or oral sounds (h, d, h).
If the nasal sound cavity is not used, we also have different speech sounds depending on the disposition of various movable organs on the mouth ( the shape of lips-rounded or unrounded ) the part of the tongue which is raised “back” central vowels, the place of articulation that we have different front consonants.
Acoustic phonetics: The study of physical characteristics of the sound:
+ Sound quality: we hear a varieties of vowels and consonants
+ Pitch: we appreciate the melody or intonation of the utterance
+ Loudness: we will agree that some sound syllables sound louder than others.
Auditory phonetics: The Study of the way listeners perceive of the sounds of a language. The ability of distinguishing different sounds are normally gained over long period of time and conditioned by the experience of handling the language.
The hearing mechanism plays a very important part in the monitoring the speech, these who are born deaf or became deaf before the acquisition of speech habits are really able to learn normal speech. Similarily, a severe hearing loss later in life is likely lead to deterioration of speech (Sự xấu đi)./.