Page:An outline of English phonetics ... with 131 illustrations (IA cu31924027389505).pdf/30

12 they carry better or can be heard at a greater distance. Thus the sound a pronounced in the normal manner can be heard at a much greater distance than the sound p or the sound f pronounced in the normal manner. It so happens that the sounds defined as vowels in § 54 are noticeably more sonorous than any other speech sounds (when pronounced in the normal manner), and that is the reason why these sounds are considered to form one of the two fundamental classes.

57. The relative sonority or carrying power of sounds depends chiefly on their quality, but also to some extent on the force of the breath with which they are pronounced. When there is no great variation in the force of the breath, the sounds defined as vowels are more sonorous than the sounds defined as consonants; open vowels (§ 80) are more sonorous than close vowels (§ 80); voiced consonants are more sonorous than breathed consonants; voiced liquid consonants (§ 66) are more sonorous than other voiced consonants. The breathed consonants have very little sonority in comparison with the voiced sounds, and the differences in sonority between the various breathed consonants are practically negligible.

58. It is in accordance with this principle of relative sonority (§ 57) that certain vowels may sometimes be used in such a way as to strike the ear as consonants. This effect occurs when a vowel of less sonority is pronounced extremely short and is immediately followed by a vowel of greater sonority. Close vowels are frequently used in this way. When so used, they are called semi-vowels. It is convenient to regard semi-vowels as consonants rather than as vowels, and to assign special symbols them. The English sounds j and w (as in yard jɑ:d, wait weit) are semi-vowels, being vowels of the types i and u respectively used in the capacity of consonants.

59. Some consonants are breathed, others are voiced (see Chap. V). To every breathed sound corresponds a voiced sound, i. e. one articulated in the same place and manner, but with voice substituted for breath, and vice versa; thus v corresponds to f, z to s, b to p. It