WHAT IS SYSTEMATIC/MODERN PHONETICS
Modern phonetics is based on the idea that each phonetic segment or phoneme is composed of a bundle of features. These features provide a good description of the phoneme. As such, phonemes are distinguished from one another on the basis of their phonetic features. The presence of a feature in the bundle of features that identify a phoneme is marked by the plus [+] symbol and the absence of the feature by the minus [-] symbol. Therefore, the phonetic features used in modern phonetics are called binary features due to their dual [±] values. For example, the allophone [ph] is said to be [+aspiration] whereas its allophone [p] is identified as [-aspiration]. The symbol [α] is used to show both [±] values. The symbol [-α] is used to show the [∓] value.
Each phoneme is, therefore, adequately represented as a matrix of binary phonetic features. All sounds marked by the same value [+ or -] for a feature belong to a natural class named after that feature. For instance, all sounds that are marked [+voice] belong in the voiced class and all sounds that are marked [-voice] belong in the voiceless class. Unlike traditional phonetics, phonemes are not given individual names in modern or systematic phonetics. Rather, the bundle of distinctive features that distinguish one phoneme from the rest is used as a description (or name) for that phoneme. For example, the nasal consonants /ŋ/, /n/, and /m/ are described as:
Each of these features describes one of the discrete activities in (or parts of) the vocal tract that are crucial to the articulation of the phoneme. It should be noted that, like in traditional phonetics, in modern phonetics, too, each phoneme may be composed of more features than are actually in its description. However, many features are predictable on the basis of other features. In our example here, the phoneme /ŋ/ is a [+voice] phoneme. However, we did not use this feature in the bundle of features that describe the phoneme because the feature [+nasal] can predict the feature [+voice]. Therefore, only the minimum inevitable number of features that differentiate between a given phoneme and the rest of sound segments should be used in the description of that phoneme. These are, thus, called the distinctive features of that phoneme. The predictable features of a phoneme are called the redundant features of that phoneme.
Phonetic features not only differentiate between phonemes but also between classes of phonemes. In fact the notion of natural classes of sounds derives from this ability of binary features. For instance, /m/, /n/, and /ŋ/ are all [+nasal] while other phonemes are [-nasal]. So, these three phonemes compose a natural class of sounds in English. A natural class is defined as: A class of phonemes in which the number of features that must be specified to define that class is smaller than the number of features required to distinguish any member of that class.
In our example, only the feature [+nasal] is required to distinguish the nasal class whereas, as you have noticed, each of the nasal phonemes /ŋ/, /n/, and /m/ needs more than three distinctive features to be identified. Nasals do not comprise the only natural class of sounds. There are, in fact, many different natural classes of sounds in the English language. The major natural classes of sounds of English are consonants, vowels, liquids, and glides. These classes can easily be distinguished from each other on the basis of values (±) they assign to the phonetic features [consonantal] and [vocalic]. Compare the following:
Before we embark on any discussion of phonetic features, we had better identify English phonemes in terms of their distinctive features.
Like other English phonemes, English vowels, too, have been identified in terms of distinctive features. However, the set of distinctive features used to identify vowels is somewhat different from the set of features used for the identification of other phonemes. English vowels are identified in terms of the following features:
Notice that all English vowels are [+syllabic] and [+voiced]. Also notice that the identification of diphthongs and triphthongs requires more than one column of features. The diphthongs would be represented by a two-column feature matrix of the vowel followed by the glide; the triphthongs would be represented by a three-column feature matrix of the vowel followed by the glide followed by the vowel.
The phonetic features that can be used for the identification of English consonants have been summarized in table 4.2. above.
The phonetic features of English glides and liquids are identified in table 4.3. below.
