What is a phonetic segment?
Phonetic segments (phones) are not physical things. They are mental constructs with physical manifestations. Linguists represent them with phonetic symbols enclosed in brackets: [p], [b], [m], [æ]. Linguists also classify phonetic segments according to their acoustic and articulatory properties. So another way to characterize them is as a bundle of phonetic features, which are usually binary to indicate the presence or lack of the feature. So [p] can also be represented as a feature bundle: [+labial], [+stop], [-voice]. Phonetic segments have a two-faced character. They can be manifested in two ways acoustic and articulatory. So feature classes can represent articulatory, acoustic, or both characteristics.
The physical manifestations of phonetic segments are dynamic, not static, in nature. That is, the articulation of [p] requires sequential and simultaneous events in the speech tract. The speaker needs a very sophisticated program of muscular coordination to produce sequences of segments, and that program of coordination can alter the pronunciation of the sequence so as to do two different things: make the segments easier to hear or easier to produce. Under noisy conditions, the articulation of the segments may be altered in different ways than it is under more casual conditions. For example, an English speaker might reduce or eliminate the vowel in the first syllable polite in casual speech, pronouncing it more like plight. Likewise, a speaker might pronounce please in emphatic speech more like police: Puh-lease! Casual speech reduces articulation, thus helping the speaker more than the hearer. Emphatic speech enhances the acoustic properties of the speech signal, thus helping the hearer more than the speaker. The two-faced character of phonetic segments affects the mental program that coordinates articulatory gestures. The operations governing such a program are motivated by the opposing interests of the speaker and the hearer. Phonology is the study of the discrepancy between the articulatory targets that the speakers intend to produce and end up producing. It is also (but maybe to a lesser degree) the study of the discrepancy between the auditory-acoustic signal that hearers receive and the string of phonetic segments that they think the speaker intended to articulate.
Consider the strings of phonetic targets that speakers try to produce. These phonetic targets differ across languages and dialects. They are phonetic segments that speakers associate with the words and morphemes of their mental lexicons. We call those phonetic segments or targets phonemes. Those are the speech sounds that speakers expect to hear and associate with the words of their language. Phonemes have to be acoustically distinct from each other in order to help us distinguish words, so phonemes are phonetic segments that can be used to distinguish words in the mental lexicon. Unfortunately, the coordination of articulatory gestures may reduce or eliminate their distinctive function in running speech. Police and please can sound a lot more like each other in casual speech than when they are carefully articulated.
Now we have a rudimentary understanding of the nature of phonetic segments or idealized phonetic targets. Notice that we are not limited to producing just the phonemes of our language. We can try to articulate foreign sounds. We can try to pronounce English with a foreign accent or in a different dialect from our native one. As long as we are speaking a language, as opposed to just making noises with our mouths, the mind will impose a program of articulatory coordination on strings of phonetic targets. To acquire proper pronunciation in a foreign dialect or language, we may need to suppress or alter parts of the articulatory program that we use to produce native pronunciations. We also may need to set up new phonetic targets as new phonemes. The sounds that we try to articulate may change, and the way we pronounce the sounds we try to articulate also changes.
Now I will present the basic idea of Natural Phonology. It is not a structuralist or generativist theory of phonology, although I’ll have more to say about that in later posts. Like generative theory (but unlike structuralist theory), Natural Phonology is explicitly a psychological approach to language. The main difference is that Natural Phonology can only be understood in terms of behavioral strategies. It posits two distinct types of strategies that directly affect speech production:
- Processes: operations that alter the articulation of a sequence of phonetic segments (or phonemes) that a speaker intends to articulate
- Rules: operations that alter the string of phonetic segments (or phonemes) that a speaker intends to articulate
From a traditional linguistic perspective, processes are purely phonological operations. Rules operate outside of phonology, although they also play a role in pronunciation. They are part of what Trubetzkoy called morphophonology.
Finally, let us consider how Rules and Processes affect foreign language acquisition. Consider native German speakers who learn to pronounce the plural of knife. Germans have a Process that governs the pronunciation of all final obstruent consonants. We hear the effect in a German accent, where the speakers pronounce a word like give as giff. To learn English articulation, native speakers of German must suppress the articulatory constraint or Process that devoices final consonants. Now, the problem with knife is that the plural form undergoes a Rule that replaces the final /f/ in the stem with /v/. German speakers must learn to try to pronounce a /v/ phoneme instead of an /f/ in order to produce standard English knives. So German speakers face a doubly difficult problem with that plural form, because they have to learn to alter the intended phonemic target in the stem while simultaneously suppressing the devoicing of the final consonant cluster. When German speakers learning English say knifes [nayfs], we do not know whether they are actually intending to pronounce a voiced consonant cluster and can’t do it or a voiceless cluster because they haven’t yet learned what to try to pronounce.
The Rule/Process dichotomy in Natural Phonology explains the fundamental psychological difference between phonological and morphonological operations. Not surprisingly, the dichotomy corresponds exactly to the psychophonetic/physiophonetic alternational dichotomy that the founder of modern phonology, Baudouin de Courtenay, first called to the attention of his linguistic peers.