Articulatory phonetics in the context of "Lip"

In articulatory phonetics, a consonant is a speech sound that is articulated with complete or partial closure of the vocal tract, except for [h], which is pronounced without any stricture in the vocal tract. Examples are [p] and [b], pronounced with the lips; [t] and [d], pronounced with the front of the tongue; [k] and [g], pronounced with the back of the tongue; [h], pronounced throughout the vocal tract; [f], [v], [s], and [z] pronounced by forcing air through a narrow channel (fricatives); and [m] and [n], which have air flowing through the nose (nasals). Most consonants are pulmonic, using air pressure from the lungs to generate a sound. Very few natural languages are non-pulmonic, making use of ejectives, implosives, and clicks. Contrasting with consonants are vowels.

Since the number of speech sounds in the world's languages is much greater than the number of letters in any one alphabet, linguists have devised systems such as the International Phonetic Alphabet (IPA) to assign a unique and unambiguous symbol to each attested consonant. The English alphabet has fewer consonant letters than the English language has consonant sounds, so digraphs like ⟨ch⟩, ⟨sh⟩, ⟨th⟩, and ⟨ng⟩ are used to extend the alphabet, though some letters and digraphs represent more than one consonant. For example, the sound spelled ⟨th⟩ in "this" is a different consonant from the ⟨th⟩ sound in "thin". (In the IPA, these are [ð] and [θ], respectively.)

Phonetics is a branch of linguistics that studies how humans produce and perceive sounds or, in the case of sign languages, the equivalent aspects of sign. Linguists who specialize in studying the physical properties of speech are phoneticians. The field of phonetics is traditionally divided into three sub-disciplines: articulatory phonetics, acoustic phonetics, and auditory phonetics. Traditionally, the minimal linguistic unit of phonetics is the phone—a speech sound in a language which differs from the phonological unit of phoneme; the phoneme is an abstract categorization of phones and it is also defined as the smallest unit that discerns meaning between sounds in any given language.

Phonetics deals with two aspects of human speech: production (the ways humans make sounds) and perception (the way speech is understood). The communicative modality of a language describes the method by which a language produces and perceives languages. Languages with oral-aural modalities such as English produce speech orally and perceive speech aurally (using the ears). Sign languages, such as Australian Sign Language (Auslan) and American Sign Language (ASL), have a manual-visual modality, producing speech manually (using the hands) and perceiving speech visually. ASL and some other sign languages have in addition a manual-manual dialect for use in tactile signing by deafblind speakers where signs are produced with the hands and perceived with the hands as well.

In articulatory phonetics, the place of articulation (also point of articulation) of a consonant is an approximate location along the vocal tract where its production occurs. It is a point where a constriction is made between an active and a passive articulator. Active articulators are organs capable of voluntary movement which create the constriction, while passive articulators are so called because they are normally fixed and are the parts with which an active articulator makes contact. Along with the manner of articulation and phonation, the place of articulation gives the consonant its distinctive sound.

Since vowels are produced with an open vocal tract, the point where their production occurs cannot be easily determined. Therefore, they are not described in terms of a place of articulation but by the relative positions in vowel space. This is mostly dependent on their formant frequencies and less on the specific tongue position and lip rounding.

In articulatory phonetics, the manner of articulation is the configuration and interaction of the articulators (speech organs such as the tongue, lips, and palate) when making a speech sound. One parameter of manner is stricture, that is, how closely the speech organs approach one another. Others include those involved in the r-like sounds (taps and trills), and the sibilancy of fricatives.

The concept of manner is mainly used in the discussion of consonants, although the movement of the articulators will also greatly alter the resonant properties of the vocal tract, thereby changing the formant structure of speech sounds that is crucial for the identification of vowels. For consonants, the place of articulation and the degree of phonation or voicing are considered separately from manner, as being independent parameters. Homorganic consonants, which have the same place of articulation, may have different manners of articulation. Often nasality and laterality are included in manner, but some phoneticians, such as Peter Ladefoged, consider them to be independent.

Acoustic phonetics is a subfield of phonetics, which deals with acoustic aspects of speech sounds. Acoustic phonetics investigates features of waveforms as they pertain to the time domain (e.g. duration, amplitude, fundamental frequency), frequency domain (e.g. frequency spectrum), or combined spectrotemporal domains. Acoustic phonetics is also concerned with how these properties relate to other branches of phonetics (e.g. articulatory or auditory phonetics), as well as abstract linguistic concepts such as phonemes, phrases, or utterances.

The study of acoustic phonetics was greatly enhanced in the late 19th century by the invention of the Edison phonograph. The phonograph allowed the speech signal to be recorded and then later processed and analyzed. By replaying the same speech signal from the phonograph several times, filtering it each time with a different band-pass filter, a spectrogram of the speech utterance could be built up. A series of papers by Ludimar Hermann published in Pflügers Archiv in the last two decades of the 19th century investigated the spectral properties of vowels and consonants using the Edison phonograph, and it was in these papers that the term formant was first introduced. Hermann also played back vowel recordings made with the Edison phonograph at different speeds to distinguish between Willis' and Wheatstone's theories of vowel production.

Auditory phonetics is the branch of phonetics concerned with the hearing of speech sounds and with speech perception. It thus entails the study of the relationships between speech stimuli and a listener's responses to such stimuli as mediated by mechanisms of the peripheral and central auditory systems, including certain areas of the brain. It is said to compose one of the three main branches of phonetics along with acoustic and articulatory phonetics, though with overlapping methods and questions.