CHAP, vii.] SPECIAL MUSCULAR MECHANISMS. 659 



the characteristic interruption or modification takes place. Thus it 

 may occur, 



1. At the lips, by the movement or position of the lips in 

 reference to each other or to the teeth, giving rise to labial conso- 

 nants. 



2. At the teeth, by the movement or position of the front part 

 of the tongue in reference to the teeth or the hard palate, giving 

 rise to dental consonants. 



3. In the throat, by the movement or position of the root of 

 the tongue in reference to the soft palate or pharynx, giving rise to 

 guttural consonants. 



Among the dentals again may be distinguished the dentals 

 commonly so called, such as T, the sibilants such as S, and the 

 lingual L, all differing in the relative position of the tongue, teeth, 

 and palate. 



Consonants may also be classified according to the character of 

 the movements which give rise to them. Thus they may be either 

 explosive or continuous. 



1. Explosives. In these the characters are given to the sound 

 by the sudden establishment or removal of the appropriate inter- 

 ruption. Thus, in uttering the labial P, the lips are first closed, 

 then an expiratory current of air is driven against them, and upon 

 their being suddenly opened, the sound is generated. Similarly, 

 the dental T is generated by the sudden removal of the interruption 

 caused by the approximation of the tip of the tongue to the front 

 of the hard palate, and the guttural K by the sudden removal of 

 the interruption caused by the approximation of the root of the 

 tongue to the soft palate. 



The labial B differs from P, inasmuch as it is accompanied by 

 vibrations of the vocal cords (that is, a vowel sound is uttered at 

 the same time), and these vibrations continue after the removal of 

 the interruption. Hence B is often spoken of as being uttered with 

 voice and P without voice ; and D and G (hard) with voice bear 

 the same relation to T and K without voice. 



The continuous consonants may further be divided into 



2. Aspirates. In these the sound is generated by a rush of 

 air through a constriction formed by the partial closure of the lips, 

 or by the raising of the tongue against the hard or soft palate, &c. 

 Thus F is sounded when the lips are brought into partial, and not 

 as in P and B into complete approximation, and a current of air is 

 driven through the narrowed opening. F is uttered without any 

 accompanying vibration of the vocal cords, i.e. without voice. With 

 voice it becomes V. 



The sibilant S is formed by a rush of air past an obstruction 

 caused by the partial closure of the teeth, the front of the tongue 



422 



