ASPIRATION
In the articulation of word-initial voiceless stop consonants, in English, there is a build up of air pressure in the oral cavity prior to the actual release of airstream at the place of articulation. Therefore, when these phonemes are produced, an increased puff of air accompanies the phonemes. This quality is called aspiration. If you light a match, hold it in front of your mouth, and say a word like Peter, you may be able to feel the aspiration of the first sound.
In broad transcription (see chapter 2), aspiration is not identified; in narrow transcription, however, a superscript h is used to identify the aspiration of the phoneme:
As you see, in these examples the feature [+aspiration] is represented with a small superscribed h. The following phonological rule identifies aspirated phonemes of English:
The rule tells us that when [-voice, -continuant] phonemes occur at the beginning of a word (i.e., occupy the word-initial position), they are always [+aspiration]. This rule is not a redundancy rule because it identifies a condition for the change to take place. That is, the "word-initial position" condition must first be met if the [-voice, -continuant] phoneme wants to become [+aspiration].
Therefore, unlike redundancy rules, phonological rules need specific conditions. They are if…then rules. The schematic representation of phonological rules (also called phonological processes) is:
X ➙ Y ⁄ Z
The rule tells us that X will rewrite as Y if the conditions identified by Z are met (that is, X rewrites as Y in the context of Z). In the above example, the phoneme which is [-voice, -continuant] rewrites as [+aspiration] in the context of word-initial position. Phonological and redundancy rules will be treated with greater detail in the following chapters.
When phonemes containing [-voice] and [-continuant] features occur at the end of a word, they are sometimes [+aspiration]. When they occur after /s/, these phonemes are always [-aspiration]. The absence of aspiration can easily be felt by comparing the pronunciation of pairs of words like pie/spy, toe/stow, kill/skill, and so on. Also notice that there is never any puff of air accompanying the articulation of English phonemes which share such phonetic features as [+voice, -continuant], or [-voice, +continuant], or [+voice, +continuant]. Such English phonemes are [-aspiration]. Thus, fricatives, nasals, liquids, glides, vowels, voiced affricates, and voiced stop consonants are always [-aspiration].
