Phonetic: Scientific description

PHONETICS

Phonetics is a scientific description of what speech sounds exist in a language. It represents how they are produced and perceived and what acoustic properties they have. Thus, it can be put in the class of natural sciences.(Omolara Daniel.I, Introductory Phonetics and Phonology of English)

Phonetics essentially seeks to trace the processes physiologically involved in sound production. It describes the ways the sounds are produced and the points at which they are articulated.(Omolara Daniel.I, Introductory Phonetics and Phonology of English)

we use certain parts of our body to produce an air stream inwards and outwards. This air stream is created intentionally to produce certain sounds. These sounds are transmitted as sound waves, which are perceived by a hearer. This hearer receives the sound wave, decodifies it and, then, interprets it.

Organs of Speech

The organs situated in the respiratory tract had been adapted by humans for speech production. Thus, from the lungs to the lips and the nose, the organs along this path are normally adapted for speech

production.(Omolara Daniel.I, Introductory Phonetics and Phonology of English)



speech consists of the variation of air pressure that has compressed air in lungs as a power source. When inhaling, the diaphragm and the intercostal muscles tighten causing the chest to expand, yielding low pressure in the lungs and air flowing in. In exhaling the muscles relax causing the chest to shrink and the air flows out because of high pressure.

Speech is present almost exclusively in exhaling. What is good to keep in mind is that the speech organs (lungs, tongue, vocal cords etc.) have originally developed to enable other human activities like breathing and eating, and have only later adapted to speech production.





The larynx is a sophisticated organ, whose part is to change the air flow from lungs into periodic pressure fluctuation. The larynx comprises of the following parts: the thyroid cartilage (adam’s apple), the vocal folds and the arytenoid cartilage. The gap between vocal cords is called the fissure of glottis or the glottis and it comprises of the vocal glottis (between the vocal folds) and of the cartilaginous glottis (between the arytenoid cartilages). Homo sapiens can control the shape of the glottis in diversified positions by using the muscles in the larynx.


Take it from: http://www.cs.tut.fi/courses/SGN-4010/fonetiikka_en.pdf