Consonants are generally the result of audible friction, as in (f), or of complete stoppage, as in (p). If the glottis is at the same time left open, as in (f, p), the consonant is “breath” or “voiceless”—if it is narrowed enough to make the chords vibrate, as in (v, b), the consonant is “voice” or “voiced”; intermediate positions producing the corresponding “whispered” consonants. Vowels are characterized negatively by the absence of audible friction or stoppage: if an (i) is formed with the tongue so close to the palate as to cause buzzing, it becomes a variety of the front consonant (j). There is, of course, no difficulty in forming a vowel with the glottis in the position for breath and whisper. Thus breath (i) may often be heard in French in such words as ainsi at the end of a sentence, the result being practically a weak form of the front-breath consonant (ç). The division between vowel and consonant is not an absolutely definite one. As we see, the closer a vowel is—that is, the narrower its configurative passage is—the more like it is to a consonant, and the more natural it is to devocalize it. Some voice consonants, on the other hand, have so little buzz that acoustically they constitute a class between consonants and vowels—a class of “vowel-like” or “liquid” consonants, such as n, m, l).
The changes in sounds which result from active narrowing of the passages admit of an important distinction as “sound modifying" and “sound-colouring,” although the distinction is not always definite. Nasality and rounding are examples of sound-modifying processes. Thus we hear a certain resemblance between (b) and (m), (i) and (y), but we regard all these four as distinct and practically independent sounds. Contraction of the pharynx, on the other hand, as also of the false glottis and windpipe, have only a sound-colouring effect: if a vowel is formed with such contractions its quality (timbre) is altered, but it still remains the same vowel. It follows from the definition of speech-sounds that they admit of a twofold classification: (1) organic and (2) acoustic. As already remarked, the older phoneticians used to classify the consonants organically, the vowels mainly from the acoustic point of view. The first to give an adequate organic classification of the vowels was the author of Visible Speech. Bell gave at the same time an independent acoustic classification of the consonants as well as the vowels. His acoustic classification consists simply in arranging the sounds in the order of their “pitches” (tone-heights). The pitches of the breath consonants are absolutely fixed in each individual pronunciation, while those of spoken vowels can be varied indefinitely within the compass of each voice by tightening the vocal chords in various ways and shortening their vibrating portions· the tighter and shorter the vibrating body, the quicker its vibrations, and the higher the tone. But when a vowel is whispered or breathed nothing is heard but the resonance of the con figurative passages, especially in the mouth, and the pitches of these resonant cavities are as fixed as those of the breath consonants; in other words, a whispered (or breathed) vowel cannot be sung. Although the absolute pitches of voiceless sounds may vary from individual to individual the relations of the pitches are constant: thus in all pronunciations (ç) and whispered (i) are the highest, breath (w) in what and whispered (u) nearly the lowest in pitch among consonants and vowels respectively.
If phonetics were an ideally perfect science there would be no occasion to discuss whether the acoustic or the organic study of the vowels and the other speech-sounds is the more important: a full description of each sound would necessarily imply (1) an exact determination of its organic formation, (2) an acoustic analysis of the sound itself, both from the objective physical point of view and from the subjective one of the impression received by the ear, and (3) an explanation of how (2) is the necessary result of (1). Even this last question has already been solved to some extent. In fact, the connection between the organic formation and the acoustic effect is often self-evident. It is evident, for instance, that (i) and (ç) owe their clear sound and high pitch to their being formed by short, narrow passages in the front of the mouth, while (u) owes its low pitch to being formed in exactly the opposite way, the sound being farther muffled and the pitch consequently still more lowered by the rounding.
One reason why it is impossible to classify the vowels exclusively on acoustic principles is that two vowels formed in quite different ways may have the same pitch. Thus the “high front-round” (y) and the "high-mixed” (i) have the same pitch, the tongue-retraction of the mixed position of the latter having the same effect as the rounding of the former. It is evident, therefore, that the fundamental classification of the vowels must, like that of the consonants, be purely organic. And although for practical purposes it is often convenient to classify sounds partly from the acoustic point of view, a full scientific treatment must keep the two points of view strictly apart, and make a special chapter of the relations between them.
Vowels.—The most obvious distinction between vowels is that which depends on the share of the lips in their articulation. In such non-round vowels as (i) and (a) the lips are passive, or even separated and spread out at their corners, by which the vowels assume a clearer resonance. If, on the other hand, the lips are actively approximated, they become the round vowels (y) and “open” (o) respectively.
owels are formed with different degrees of rounding. As a general rule, the narrowness of the lip-passage corresponds to the narrowness of the mouth-passage. Thus, in passing from the vowel of too to those of no and saw the back of the tongue is progressively lowered, and the rounding is diminished in the same proportion.
But there is also abnormal rounding. Thus, if we pronounce (o) with the lips in the position they have in forming (u), the resulting “over-rounded” vowel sounds half-way between (o) and (u); the second element of the diphthong (ou) in go is formed in this way. Conversely, the (u) in put is “under-rounded” in the North of England: the tongue position is kept, but the lips are only brought together a little at the corners, as in (ɔ).
The mouth positions of the vowels are the result of two factors: (1) the height of the tongue—its nearness to the palate—and (2) the degree of its retraction. Bell distinguishes three degrees of height: in his system (u) is “high,” the (o) of boy is “mid,” and the (ɔ) of saw is “low.” He also has three degrees of retraction: in “back” vowels, such as (u), the root of the tongue is drawn to the back of the mouth, and the whole tongue slopes down from back to front. In “front” vowels, such as (i), the front of the tongue is raised towards the hard palate, so that the tongue slopes down from front to back.
Most of these slope-positions yield vowels of a distinct and clear resonance. There is also a class of “flat” vowels. such as (a), in which the tongue is in a more or less neutral position. If the tongue is raised from the low-flat position of (əə) in bird to the high position, we get the (i) of North Welsh dyn “man,” which, as already observed, is acoustically similar to (y).
The flat vowels were called “mixed” by Bell, in accordance with his view that they are the result of combining back and front articulation. And although this view is now generally abandoned, the term “mixed” is still retained by the English school of phoneticians.
In this way Bell mapped out the whole mouth by the following cardinal points:—
| high-back | high-mixed | high-front |
| mid-back | mid-mixed | mid-front |
| low-back | low-mixed | low-front |
In this arrangement “high-back,” &c., are fixed points like those of latitude and longitude. Thus normal “high” means that the tongue is raised as close to the palate as is possible without causing consonantal friction, and “back” implies retraction of the same kind. Intermediate positions are defined as “raised,” “lowered,” “inner,” “outer.”
The most original and at the same time the most disputed part of Bell's vowel-scheme is his distinction of “primary” and “wide.” All vowels fall under one of these categories. Thus, the primary French (i) and the corresponding English wide (i) are both high front-vowels, and yet they are distinct in sound: the English vowel is a semitone lower in pitch. Bell explained the greater openness of the wide vowels as the result of greater expansion of the pharynx; and he considered the other class to be most nearly allied to the consonants—whence their name “primary”—the voice-passages in the formation of primary vowels being expanded only so far as to remove all fricative quality. But alterations in the shape of the pharynx have only a sound-colouring, not a sound-modifying, effect; and Sweet showed that the distinction depends on the shape of the tongue, and accordingly substituted “narrow” for Bell's “primary.” He also showed that the distinction applies to consonants as well as vowels: thus the narrow French (w) in oui is a consonantization of the narrow French (u) in sou, while the English (w) preserves the wide quality of the (u) in put.
In forming narrow sounds there is a feeling of tension in that
