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What is a natural class?

 

Definition
 

A natural class is a set of sounds that have certain phonetic features in common.

 

All the members of a natural class are affected in the same way in the same environment. Similarly, all members of a natural class have the same effect on other sounds that occur in their environment.

 

For a group of sounds to constitute a natural class,

 
  • they must all share one or more features and
  • there should be no other sounds in the language that have this feature or combination of features.
Examples (Isthmus Zapotec, Mexico)
 
  • Voiced plosives {b, d, g} form a natural class. All the members of the set are affected the same way in the same environment.
  • For example, following the voiceless S (possessive prefix), voiced plosives are realized as the corresponding voiceless plosives. These voiceless plosives form another natural class {p, t, k}:

    bere

    ‘chicken’

    S-pere-be

    ‘his chicken’

    biuuza?

    ‘guest’

    S-piuuza-be

    ‘his guest’

    daa

    ‘mat’

    S-taa-be

    ‘his mat’

    doo

    ‘rope’

    S-too-be

    ‘his rope’

    geta

    ‘tortilla’

    S-keta-be

    ‘his tortilla’

    gamiZa?

    ‘shirt’

    S-kamiZa-be

    ‘his shirt’

    Source:

    Merrifield 1987 80

  • Examples (English)
     
  • Voiceless plosives form a natural class. They all have the same effect on voicing a following fricative (realized as [s]). Likewise, voiced plosives form a natural class and all have the same effect on a following fricative (realized as [z]).

    map[s]

    tab[z]

    cup[s]

    cub[z]

    mat[s]

    fad[z]

    hit[s]

    bid[z]

    pack[s]

    rag[z]

    tick[s]

    leg[z]

    Source:

    Burquest and Payne 1993 10

  • Kinds
     

    Here are some kinds of natural classes:

     
    • Plosive
    • Coronal consonant
    • Voiced fricative
    • Voiceless fricative
    • Rounded vowel
    • Sonorant

    Context for this page:

    Go to SIL home page This page is an extract from the LinguaLinks Library, Version 5.0 published on CD-ROM by SIL International, 2003. [Ordering information.]

    Page content last modified: 5 January 2004

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