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Department of Linguistics


Distinction Between Consonants and Vowels

Robert Mannell

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The distinction between vowels and consonants is based on three main criteria:-

  1. physiological: airflow / constriction
  2. acoustic: prominence
  3. phonological: syllabicity

Sometimes, it is necessary to rely on two or three of these criteria to decide whether a sound is a vowel or a consonant.

Physiological Distinction

In general, consonants can be said to have a greater degree of constriction than vowels. This is obviously the case for oral and nasal stops, fricatives and affricates. The case for approximants is not so clear-cut as the semi-vowels /j/ and /w/ are very often indistinguishable from vowels in terms of their constriction.

Acoustic Distinction

In general, consonants can be said to be less prominent than vowels. This is usually manifested by vowels being more intense than the consonants that surround them. Sometimes, certain consonants can have a greater total intensity than adjacent vowels but vowels are almost always more intense at low frequencies than adjacent consonants.

Phonological Distinction

Syllables usually consist of a vowel surrounded optionally by a number of consonants. A single vowel forms the prominent nucleus of each syllable. There is only one peak of prominence per syllable and this is nearly always a vowel. The consonants form the less prominent valleys between the vowel peaks. This tidy picture is disturbed by the existence of syllabic consonants. Syllabic consonants form the nucleus of a syllable that does not contain a vowel. In English, syllabic consonants occur when an approximant or a nasal stop follows a homorganic (same place of articulation) oral stop (or occasionally a fricative) in words such as "bottle" /bɔtl̩/ or "button" /bʌtn̩/.

The semi-vowels in English play the same phonological role as the other consonants even though they are vowel-like in many ways. The semi-vowels are found in syllable positions where stops, fricatives, etc. are found (eg. "pay", "may", and "say" versus "way").