Sound classes

The sounds of languages can be grouped into classes on the basis of phonetic properties they share. The most basic division among sounds is into two classes: VOWELS and CONSONANTS.

From a phonetic point of view, vowels are articulated with no one part of the mouth closed, the sound of the air passing between the vocal organs is not heard. From a phonological point of view, vowels are units of the sound system which typically occupy the middle of a syllable, as in CAT or BIG. Vowels involve the vibration of the vocal cords, and shaping of the mouth. The most widely used method of describing and analysing the articulation of vowels was devised by Daniel Jones and is known as the CARDINAL VOWEL SYSTEM.

With some changes, the following chart answers four questions for English vowels: 1. Height: high, mid or low? 2. Place: front, central or back? 3. Lips: rounded or unrounded? 4. Tongue Root: advanced or retracted (tense or lax)?

Height. According to their tongue height (which is the vertical distance between the upper surface of the tongue and the palate), vowels are divided into high (close), mid, and low (open).

Place: According to their frontness or backness (i.e. the horizontal movement of the tongue), vowels can be front, central and back.

Lips: unrounded or rounded.

Tongue Root: tense or lax.

This describes the most difficult vowel feature to feel, due to the lack of appropriate nerves in the root of the tongue and throat. The tongue root can be advanced (tense state), making the throat wider. It can also be retracted (lax state), narrowing the throat, Thus [ʊ] can be described as “high back rounded tense”, [æ] as “low front unrounded lax”. The vowels [ʌ] and [∂] share the resting position features: mid, central, unrounded and lax.

English vowels can also be classified according to the stability of articulation. MONOPHTHONGS are made by a movement of the tongue toward one position in the mouth. DIPHTHONGS are vowels which consist of a movement, or glide, from one position to another. Eight English diphthongs are grouped into three types, depending on the tongue movement involved. Three Central diphthongs end with a glide towards the schwa vowel, as in the words HERE, AIR, and SURE. Closing diphthongs end with a glide towards a higher position in the mouth. They end with either /i/(as in THEY, CRY, TOY), or /ʊ/ (as in SO, HOW). All English diphthongs are falling, i.e. the first element is stressed more than the second. Other languages have rising diphthongs, where the second element is stressed, as in Italian ‘uomo’ (man) and ‘uovo’ (egg). A TRIPHTHONG is a glide from one vowel to another and then to a third, all produced rapidly and without interruption. Triphthongs are formed by adding a central glide to the closing diphthongs, and can be heard in the words FIRE, FLOUR.

Yet another classification considers the length factor: twelve English monophthongs are subdivided into five long vowels /і: ɑ: ɔ: u: ɜ:/ and seven short ones /ɪ e æ ʌ ɒ ʊ ə/. In connected speech long vowels may be of the same length as short ones.

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