phonetics

The identification, description, and classification of sounds used in articulate speech. These sounds are codified in the International Phonetic Alphabet (IPA), a highly modified version of the Roman alphabet.

The IPA is based on ordinary Roman letters, along with modified forms, letters from other alphabets, and some invented letters. There are also a number of accents and other diacritics. Each symbol stands for a particular sound, but the interpretation of a sequence of symbols also depends on a number of conventions and on the phonetic context.

Articulatory phonetics This involves the analysis of the movements of the speech organs. The basic movements, or articulations, can be classified according to manner and place of articulation. Types of sound based on manner of articulation include plosives, affricates, nasals, laterals, rolls, fricatives, continuants, and vowels. A sound can also be classified according to its place of articulation: active articulators are the lips, parts of the tongue (tip, blade, centre, back, and root), and the vocal cords; passive articulators include the upper front teeth and the roof of the mouth (hard palate and soft palate). The soft palate also functions as an active articulator against the back wall of the throat or pharynx. The set of categories based on the vocal apparatus involved includes bilabial, labiodental, dental, alveolar, palatal, velar, uvular, and glottal. Any consonant may be broadly defined in terms of these two categories, by describing the manner and place of articulation. Vowels are sounds in which the tongue does not constrict the air passage enough to produce a fricative consonant. They are classified by stating which part of the body of the tongue is raised, and by how much.

Acoustic phonetics While articulatory phonetics deals with the speaker, acoustic phonetics deals with the listener. Ear training is a fundamental requirement for phonetic work, to enable the distinction of different sounds; the basic technique consists of dictation of meaningless material, which compels the transcriber to pay attention to sound rather than meaning.

Instrumental phonetics Various kinds of apparatus are used in instrumental phonetics, also known as experimental phonetics. Both articulatory and acoustic processes can be investigated instrumentally. Instruments can be used to make very accurate analyses of the complex sounds reaching our ears. Acoustic analysis shows that sounds in nature are rarely simple, but are composed of a combination or series of tones that we are unable to perceive separately, but which affect our estimation of quality, such as the character of different musical instruments, or of different voices. It is only by instrumental techniques that the component parts of a complex sound can be revealed and measured.