Approximant


Approximants are speech sounds that involve the articulators approaching each other but not narrowly enough, nor with enough articulatory precision, to create turbulent airflow. Therefore, approximants fall between fricatives, which produce a turbulent airstream, and vowels, which produce no turbulence. This class is composed of sounds like and semivowels like and , as well as lateral approximants like .

Terminology

Before Peter Ladefoged coined the term approximant in the 1960s, the terms frictionless continuant and semivowel were used to refer to non-lateral approximants.
In phonology, approximant is also a distinctive feature that encompasses all sonorants except nasals, including vowels, taps, and trills.

Semivowels

Some approximants resemble vowels in acoustic and articulatory properties and the terms semivowel and glide are often used for these non-syllabic vowel-like segments. The correlation between semivowels and vowels is strong enough that cross-language differences between semivowels correspond with the differences between their related vowels.
Vowels and their corresponding semivowels alternate in many languages depending on the phonological environment, or for grammatical reasons, as is the case with Indo-European ablaut. Similarly, languages often avoid configurations where a semivowel precedes its corresponding vowel. A number of phoneticians distinguish between semivowels and approximants by their location in a syllable. Although he uses the terms interchangeably, remarks that, for example, the final glides of English par and buy differ from French par and baille in that, in the latter pair, the approximants appear in the syllable coda, whereas, in the former, they appear in the syllable nucleus. This means that opaque contrasts can occur in languages like Italian and Spanish.
In articulation and often diachronically, palatal approximants correspond to front vowels, velar approximants to back vowels, and labialized approximants to rounded vowels. In American English, the rhotic approximant corresponds to the rhotic vowel. This can create alternations.
In addition to alternations, glides can be inserted to the left or the right of their corresponding vowels when they occur next to a hiatus. For example, in Ukrainian, medial triggers the formation of an inserted that acts as a syllable onset so that when the affix is added to футбол to make футболіст 'football player', it is pronounced, but маоїст, with the same affix, is pronounced with a glide. Dutch for many speakers has a similar process that extends to mid vowels:
  • bioscoop →
  • zee + en →
  • fluor →
  • reu + en →
  • Rwanda →
  • Boaz →
Similarly, vowels can be inserted next to their corresponding glide in certain phonetic environments. Sievers' law describes this behaviour for Germanic.
Non-high semivowels also occur. In colloquial Nepali speech, a process of glide-formation occurs, where one of two adjacent vowels becomes non-syllabic; the process includes mid vowels so that features a non-syllabic mid vowel. Spanish features a similar process and even nonsyllabic can occur so that ahorita is pronounced. It is not often clear, however, whether such sequences involve a semivowel or a diphthong, and in many cases, it may not be a meaningful distinction.
Although many languages have central vowels, which lie between back/velar and front/palatal, there are few cases of a corresponding approximant. One is in the Korean diphthong or though it is more frequently analyzed as velar, and Mapudungun may be another, with three high vowel sounds,,, and three corresponding consonants,, and, and a third one is often described as a non-labialized voiced velar fricative; some texts note a correspondence between this approximant and that is parallel to – and –. An example is liq .
It has been noted that the expected symbols for the approximant correlates of are or.

Approximants versus fricatives

In addition to less turbulence, approximants also differ from fricatives in the precision required to produce them. When emphasized, approximants may be slightly fricated, which is reminiscent of fricatives. For example, the Spanish word ayuda features a palatal approximant that is pronounced as a fricative in emphatic speech. Spanish can be analyzed as having a meaningful distinction between fricative, approximant, and intermediate. However, such frication is generally slight and intermittent, unlike the strong turbulence of fricative consonants.
For places of articulation further back in the mouth, languages do not contrast voiced fricatives and approximants. Therefore, the IPA allows the symbols for the voiced fricatives to double for the approximants, with or without a lowering diacritic.
Occasionally, the glottal "fricatives" are called approximants, since typically has no more frication than voiceless approximants, but they are often phonations of the glottis without any accompanying manner or place of articulation.

Central approximants

Approximants with a dedicated IPA symbol are in bold. Letters shown with the lowered diacritic are often transcribed without it; the diacritic is used here to distinguish from their fricative counterparts.
  • bilabial approximant
  • labiodental approximant
  • dental approximant
  • alveolar & post-alveolar approximants
  • retroflex approximant
  • palatal approximant
  • velar approximant
  • uvular approximant
  • pharyngeal approximant
  • epiglottal approximant

    Glottal approximants

Glottal approximants may be best described as placeless with only laryngeal specification, as they take on the shapes of surrounding sounds in their articulation.
  • voiceless glottal approximant
  • breathy-voiced glottal approximant
  • creaky-voiced glottal approximant

    Lateral approximants

In lateral approximants, the center of tongue makes solid contact with the roof of the mouth. However, the defining location is the side of the tongue, which only approaches the teeth, allowing free passage of air.
There was once some controversy over whether voiceless approximants could even exist, with the argument that voiceless airflow is necessarily turbulent and therefore by definition produces a fricative sound, but more recent research distinguishes between turbulent and laminar airflow in the vocal tract, with voiced fricatives characterized by more strongly turbulent airflow than voiceless fricatives due to tighter glottal constriction. Ball & Rahilly state that "the airflow for voiced approximants remains laminar, and does not become turbulent," and that with voiceless approximants is "usually somewhat turbulent" and that because of this the distinction between voiceless approximants and voiceless fricatives is not always clear.

Phonetic characteristics

consonants are generally said to be the result of turbulent airflow at a place of articulation in the vocal tract. However, an audible voiceless sound may be made without this turbulent airflow: makes a distinction between "local friction" and "cavity friction". More recent research distinguishes between "turbulent" and "laminar" airflow in the vocal tract. It is not clear if it is possible to describe voiceless approximants categorically as having laminar airflow as a way of distinguishing them from fricatives. write that "the airflow for voiced approximants remains laminar, and does not become turbulent. Voiceless approximants are rare in the languages of the world, but when they do occur the airflow is usually somewhat turbulent." Audible voiceless sounds may also be produced by means of turbulent airflow at the glottis, as in ; in such a case, it is possible to articulate an audible voiceless sound without the production of local friction at a supraglottal constriction. describes such sounds, but classes them as sonorants.

Distinctiveness

Voiceless approximants are rarely if ever distinguished phonemically from voiceless fricatives in the sound system of a language. discuss the issue and conclude "In practice, it is difficult to distinguish between a voiceless approximant and a voiceless fricative at the same place of articulation ... there is no evidence that any language in the world makes such a distinction crucial."

Disagreement over use of the term

Voiceless approximants are treated as a phonetic category by ,, and. However, the term voiceless approximant is seen by some phoneticians as controversial. It has been pointed out that if approximant is defined as a speech sound that involves the articulators approaching each other but not narrowly enough to create turbulent airflow, then it is difficult to see how a voiceless approximant could be audible. As John C. Wells puts it in his blog, "voiceless approximants are by definition inaudible ... If there's no friction and no voicing, there's nothing to hear." A similar point is made in relation to frictionless continuants by : "There are no voiceless frictionless continuants because this would imply silence; the voiceless counterpart of the frictionless continuant is the voiceless fricative." argue that the increased airflow arising from voicelessness alone makes a voiceless continuant a fricative, even if lacking a greater constriction in the oral cavity than a voiced approximant.
argue that Burmese and Standard Tibetan have voiceless lateral approximants and Navajo and Zulu voiceless lateral fricatives, but also say that "in other cases it is difficult to decide whether a voiceless lateral should be described as an approximant or a fricative". compared voiceless laterals in Estonian Swedish, Icelandic, and Welsh and found that Welsh-speakers consistently used, that Icelandic-speakers consistently used, and that speakers of Estonian Swedish varied in their pronunciation. They conclude that there is "a range of variants within voiceless laterals, rather than a categorical split between lateral fricatives and voiceless approximant laterals".