a) Features establish natural classes
Using distinctive features, phonemes are broken down into smaller components. For example, a nasal phoneme /m/ might be represented as a feature matrix [+ sonorant, -continuant, +voice, +nasal, +labial] (nb. you will often see the features of the matrices arranged in columns in phonology books -- this is exactly equivalent to the 'horizontal' representation used here). By representing /m/ in this way, we are saying both something about its phonetic characteristics (it's a sonorant because, like vowels, its acoustic waveform has low frequency periodic energy; it's a non-continuant because the airflow is totally interrupted in the oral cavity etc.), but also importantly, the aim is to choose distinctive features that establish natural classes of phonemes. For example, since all the other nasal consonants and nasalised vowels (if a language has them) have feature matrices that are defined as [+nasal], we can refer to all these segments in a single simple phonological by making the rule apply to [+nasal] segments. Similarly, if we want our rules to refer to all the approximants and high vowels, we might define this natural class by [+sonorant, +high].
The advantage of this approach is readily apparent in writing phonological rules. For example, we might want a rule which makes approximants voiceless when they follow aspirated stops in English. If we could not define phonemes in terms of distinctive features, we would have to have separate rules, such as [l] becomes voiceless after /k/ ('claim'), /r/ becomes voiceless after /k/ ('cry'), /w/ becomes voiceless after /k/ ('quite'), /j/ becomes voiceless after /k/ ('cute'), and then the same again for all the approximants that can follow /p/ and /t/. If we define phonemes as bundles of features, we can state the rule more succinctly as e.g. [+sonorant, -syllabic, +continuant] sounds (i.e. all approximants) become [+spread glottis] (aspirated) after sounds which are [+spread glottis] (aspirated).
If the features are well chosen, it should be possible to refer to natural classes of phonemes with a small number of features. For example, [p t k] form a natural class of voiceless stops in most languages: we can often refer to these and no others with just two features, [-continuant, -voiced]. On the other hand, [m] and [d] are a much less natural class (ie. few sound changes and few, if any, phonological rules, apply to them both and appropriately it is impossible in most feature systems to refer to these sounds and no others in a single feature matrix).
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Chomsky and Halle (1968-1983)
a) Features establish natural classes
Using distinctive features, phonemes are broken down into smaller components. For example, a nasal phoneme /m/ might be represented as a feature matrix [+ sonorant, -continuant, +voice, +nasal, +labial] (nb. you will often see the features of the matrices arranged in columns in phonology books -- this is exactly equivalent to the 'horizontal' representation used here). By representing /m/ in this way, we are saying both something about its phonetic characteristics (it's a sonorant because, like vowels, its acoustic waveform has low frequency periodic energy; it's a non-continuant because the airflow is totally interrupted in the oral cavity etc.), but also importantly, the aim is to choose distinctive features that establish natural classes of phonemes. For example, since all the other nasal consonants and nasalised vowels (if a language has them) have feature matrices that are defined as [+nasal], we can refer to all these segments in a single simple phonological by making the rule apply to [+nasal] segments. Similarly, if we want our rules to refer to all the approximants and high vowels, we might define this natural class by [+sonorant, +high].
The advantage of this approach is readily apparent in writing phonological rules. For example, we might want a rule which makes approximants voiceless when they follow aspirated stops in English. If we could not define phonemes in terms of distinctive features, we would have to have separate rules, such as [l] becomes voiceless after /k/ ('claim'), /r/ becomes voiceless after /k/ ('cry'), /w/ becomes voiceless after /k/ ('quite'), /j/ becomes voiceless after /k/ ('cute'), and then the same again for all the approximants that can follow /p/ and /t/. If we define phonemes as bundles of features, we can state the rule more succinctly as e.g. [+sonorant, -syllabic, +continuant] sounds (i.e. all approximants) become [+spread glottis] (aspirated) after sounds which are [+spread glottis] (aspirated).
If the features are well chosen, it should be possible to refer to natural classes of phonemes with a small number of features. For example, [p t k] form a natural class of voiceless stops in most languages: we can often refer to these and no others with just two features, [-continuant, -voiced]. On the other hand, [m] and [d] are a much less natural class (ie. few sound changes and few, if any, phonological rules, apply to them both and appropriately it is impossible in most feature systems to refer to these sounds and no others in a single feature matrix).
Using distinctive features, phonemes are broken down into smaller components. For example, a nasal phoneme /m/ might be represented as a feature matrix [+ sonorant, -continuant, +voice, +nasal, +labial] (nb. you will often see the features of the matrices arranged in columns in phonology books -- this is exactly equivalent to the 'horizontal' representation used here). By representing /m/ in this way, we are saying both something about its phonetic characteristics (it's a sonorant because, like vowels, its acoustic waveform has low frequency periodic energy; it's a non-continuant because the airflow is totally interrupted in the oral cavity etc.), but also importantly, the aim is to choose distinctive features that establish natural classes of phonemes. For example, since all the other nasal consonants and nasalised vowels (if a language has them) have feature matrices that are defined as [+nasal], we can refer to all these segments in a single simple phonological by making the rule apply to [+nasal] segments. Similarly, if we want our rules to refer to all the approximants and high vowels, we might define this natural class by [+sonorant, +high].
The advantage of this approach is readily apparent in writing phonological rules. For example, we might want a rule which makes approximants voiceless when they follow aspirated stops in English. If we could not define phonemes in terms of distinctive features, we would have to have separate rules, such as [l] becomes voiceless after /k/ ('claim'), /r/ becomes voiceless after /k/ ('cry'), /w/ becomes voiceless after /k/ ('quite'), /j/ becomes voiceless after /k/ ('cute'), and then the same again for all the approximants that can follow /p/ and /t/. If we define phonemes as bundles of features, we can state the rule more succinctly as e.g. [+sonorant, -syllabic, +continuant] sounds (i.e. all approximants) become [+spread glottis] (aspirated) after sounds which are [+spread glottis] (aspirated).
If the features are well chosen, it should be possible to refer to natural classes of phonemes with a small number of features. For example, [p t k] form a natural class of voiceless stops in most languages: we can often refer to these and no others with just two features, [-continuant, -voiced]. On the other hand, [m] and [d] are a much less natural class (ie. few sound changes and few, if any, phonological rules, apply to them both and appropriately it is impossible in most feature systems to refer to these sounds and no others in a single feature matrix).
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