Vowels, Consonants and Glides

The sounds of language can be grouped into classes, based on the phonetic properties that they share. The most basic division among speech sounds is into two major classes, vowels and consonants. Another class of sounds, the glides, shares properties of both vowels and consonants. Each of these classes of sounds has a number of distinguishing distinctive features.

Vowels and consonants can be distinguished on the basis of differences in articulation, as well as acoustically and functionally.

Consonants are made with a narrow or complete closure in the vocal tract. The airflow is either blocked momentarily, meets an obstacle on its way, or restricted so much that noise is produced as air flows past the constriction. Vowels are produced with little or no obstruction in the vocal tract.

As a result of the difference in articulation , consonants and vowels differ in the way they sound (see Table 2.1).Vowels are more sonorous than consonants - that is, we perceive them as louder and longer lasting than consonants.

The greater sonority of vowels allows them to form the basis of syllables. A syllable can be best understood as a peak of sonority surrounded by less sonorous segments. In counting the syllables of words, we are in effect counting the number of vowels. A vowel is thus said to form the nucleus of a syllable. The so-called "Syllabic Liquids and Nasals" will show that certain types of consonants can form syllabic nuclei as well.

Table 4. The major differences between consonants and vowels

A type of speech sound that shows properties of both consonants and vowels is called a glide. Glides may be thought as rapidly articulated vowels; this is the auditory impression they produce. Glides are produced with an articulation like that of a vowel. However, they move quickly to another articulation, as do the initial glides in yet or wet, or quickly terminate, as do the word-final glides in boy or now.

Even though they are vowellike in articulation, glides function as consonants. For example, glides can never form the nucleus of a syllable. Since glides show properties of both consonants and vowels, it is no wonder that the terms semivowel (for the Romanian language) or semiconsonant are used interchangeably with the term glide.