APPROXIMANT
An approximant is a consonant that makes very little obstruction to the airflow. Approximants are divided into two main groups: semivowels (also called glides) and liquids. The semivowels are /h/ as in hat /hæt/, /j/ as in yellow /ˈjeləʊ/, and /w/ as in one /wʌn/. They are very similar to the vowels /ɜ:/, /u:/ and /i:/, respectively. However, semivowels are produced as a rapid glide. The liquids include the lateral /l/ and /r/ sounds in that these sounds have an identifiable constriction of the airflow, but not one sufficiently obstructive enough to produce a fricative sound. Approximants are never fricative and never completely block the flow of air.
[h] is an interesting case. It is a voiceless glottal fricative. The glottis is almost completely closed, except for a narrow opening (i.e., the posterior shunt) in its upper part at the level of the arythenoidal cartilage. A strong friction develops when air flows through this opening.
One point of caution is, however, necessary here. English and Persian make use of different forms of the approximant /r/. On the whole, the approximant /r/ is of three types: (a) flap, (b) trill, and (c) retroflex. English draws on trill and retroflex types while Persian employs trill and flap types. In Persian, the /r/ sound becomes flap whenever it appears between two vowels. A flap /r/ is articulated when the blade of the tongue touches the roof of the mouth only once. Try saying the following Persian words to yourselves:
You should be able to feel the /r/ sound in these Persian words. It is somewhat similar to the pronunciation of the intervocalic (between two vowels) /t/ sound in American pronunciation of such words as 'water', 'butter', 'better', etc. Notice, however, that English lacks flap /r/. The trill /r/ is articulated when the blade of the tongue repeatedly touches the roof of the mouth for several times (similar to the noise made by a chain gun). The /r/ sound in the Russian language is an example of the extreme case of trill /r/. Both English and Persian employ trill /r/. The retroflex /r/ is specific to English. Whenever the /r/ sound starts a word in English, it becomes retroflex: (a) the tip of the tongue curls back, (b) the upper and lower teeth approach each other, and (c) the lips are rounded and sent forward. Hence, the retroflex /r/. try saying the English words 'write', 'red', etc. to yourselves. They start with retroflex /r/.
Many phoneticians use the term vibrant to refer to these and similar consonants. Vibrant consonants involve one or more tapping or flapping vibrations of the speech organs under pressure from the airstream. Part of the tongue makes contact with the palate, most commonly at the alveolar ridge, the soft palate, or (in some languages) the uvula. One or more very brief occlusions (or air blockage) occur successively, accompanied by short resonances. Vibrants are generally voiced. In narrow transcription, a small subscript circle may be added to any IPA symbol to indicate a voiceless variant. There are two distinct classes of vibrants: (a) those with only one vibration, called taps, and (b) those with multiple vibrations, called trills. [ɾ] is an alveolar tap (sometimes called flap). The alveolar region serves as the target for the tongue tip, which vibrates there briefly before falling back to rest against the lower teeth. [ɽ] is a retroflex tap. The tip of the tongue curves up and back, and its underside vibrates briefly against the roof of the mouth, before falling back to rest against the lower teeth. [r] is an alveolar trill. The alveolar region serves as the target for the tongue tip, which vibrates there under pressure from the airstream behind. The vibration produces occlusive sounds and vocalic-type resonances in rapid alternation. This is the famous rolled /r/ of Spanish, Russian, and some other languages.
