Approximants

Liquids and glides form the category of approximants. These sounds are made in such a way that one articulator is close to another without narrowing the  vocal tract to create any friction. Approximants are joined with stops in two-member English onset clusters, as in play [ple], green [gɹ̣in], twin [twɪn], beauty [bjuti]. In addition to this general pattern, certain members of this class have specific combinatorial characteristics. The lateral liquid /l/ can be com bined with /s/ (e.g. sleep [slip]) and /f/ (e.g. fly [flaɪ]), and the non-lateral liquid /ɹ̣/ can combine with /f/ (e.g. free [fɹ̣i]), /θ/ (e.g. three [θɹ̣i]), and /ʃ/ (e.g. shrimp [ʃɹ̣ɪmp]). The labio-velar glide /w/ can follow a /s/ (e.g. sweet [swit]) and /θ/ (e.g. thwart [θwɔɹ̣t]) in clusters, while the possibilities are more numerous for the palatal glide /j/ (e.g. /m/ music [mjuzɪk], /f/ few [fju], /v/ view [vju], and /h/ hue [hju]). When the first member of the cluster is a voice less obstruent, approximants are devoiced ([gɹ̣in] but [pɹ̥e], [glu] but [sl̥ip], [dwɪndl̩] but [sw̥it]).

The palatal glide /j/ is articulated with an audible friction before /i/ or /ɪ/ (e.g. year [jiɹ̣], yip [jɪp]), while there is no friction with other vowels (e.g. yes [jεs], yacht [jɑt], yawn [jɔn]). Another point to be made about /j/ is that it is restricted to appearing before /u/ in initial clusters (e.g. music [mjuzɪk], pure [pjuɹ̣]).

The labio-velar glide /w/ is unique among the consonants of English, as it involves two places of articulation. While we have lip rounding (thus, labial), the back part of the tongue is also raised toward the velum (thus, velar) in the production of this sound.

The liquids, /l, ɹ̣/, differ from the glides in one important respect: they can be syllabic in English. The conducive environment for the syllabicity of the liquids is similar, but not identical, to that of the nasals we examined earlier. Nasals required an obstruent as the preceding segment to become syllabic, while liquids can accept any consonant for this condition. For example, in words such as channel [tʃænl̩], kennel [kεnl̩], the final syllable has the syllabic liquid after a sonorant consonant. Also worth mentioning is the lack of the requirement of homorganicity between the syllabic liquids and the preceding consonant. Unlike nasals, which overwhelmingly require homorganicity with the preceding obstruent, syllabic liquids have the freedom to occur after consonants with different places of articulation, as exemplified by apple [æpl̩], removal [ɹ̣əmuvl̩], pickle [pɪkl̩], eagle [igl̩].

We should also add, in parallel to what was said in relation to nasals, that whenever the consonant that precedes the lateral is preceded by another consonant, we normally insert an [ə] between the liquid and the consonant preceding it, and thus, the liquid does not become syllabic. Examples such as pistol [pɪstəl] not [pɪstl], tingle [tɪŋgəl] not [tɪègl̩], and candle [kændəl] not [kændl] illustrate this clearly. Finally, when the syllabic [l̩] is followed by an unstressed vowel, its loss of syllabicity is variable; traveling and traveler have either two or three syllables.

The alveolar lateral liquid, /l/, which is produced with varying degrees of ‘velarization’ (i.e. raising the back of the tongue), is articulated in a more forward (dental) fashion when it is followed by an interdental fricative (e.g. wealth [wεl̪θ], kill them [kɪl̪ðεm]).

The retroflex approximant /ɹ̣/ is produced with the tip of the tongue curled back toward the hard palate in AE. However, this is not the only way to produce the /ɹ̣/ in AE. Some speakers have no retroflexion and use a ‘bunched’ articulation. The /ɹ̣/ is produced with friction (affricated) in onset clusters after the alveolar stops (e.g. try, dry). It is commonplace to use a ‘retracted’ diacritic for this phenomenon (e.g. [tɹ̱aɪ]).