Sometimes, but rarely, syllables are uttered _tremulously_, or with a _tremor_; that is, with constituent intervals of less than a semitone, uttered discretely in rapid succession, and passing, in the aggregate, through an interval of more or less width. An exaggerated form of this utterance may be heard in the neighing of a horse. EXERCISE.--1. Utter the syllable _pae_ as a concrete, with rising and falling intervals, severally, of a _second_, _third_, _fifth_, and an _octave_; also with intervals of a _semitone_; also with a _tremor_. Let the exercise be varied so as to include many degrees of initial pitch. Use a diagram of a musical staff for reference. 2. Read with exaggerated impressiveness, "_Am_ =I= _to be your slave?_ =No!=" In the pronunciation of the letter [=a], as in _pate_, two sounds are heard: the first is that of the name of the letter, which is uttered with some degree of fulness; the second is that of _[=e]_ in _mete_, but, as it were, tapering and vanishing;--in the meantime the voice traverses a rising interval of one tone, that is, of a second. The utterance of these two sounds, although the sounds themselves are distinct, is completely continuous, from the full opening of the one to the vanishing close of the other, and it is impossible to say where the first ends and where the last begins. It is essential, however, to consider them separately. The first is called the =radical movement=, and the second the =vanishing movement=; and these together constitute the entire concrete. All the vowels do not equally well exemplify in their utterance a _distinction of sound_ in their radical and vanishing movements, because some vowel sounds are less diphthongal than others, and some, again, are pure monophthongs; but _these two movements and the concrete variation of pitch, the result of one impulse of the voice, are the essential structure of every syllable_, and are characteristic of speech-notes as contradistinguished from those of song. When the radical and vanishing movements are effected smoothly, distinctly, and without intensity or emotion, commencing fully and with some abruptness, and terminating gently and almost inaudibly, the result is the =equable concrete=. This of course may be produced with intervals, either upward or downward, of any degree--tone, semitone, third, fifth, or octave. It must be said, however, that some syllables, and even some vowels, lend themselves more easily than others to that prolonged utterance which is essential to the production of wide intervals and the perfectness of the vanishing movement. The equable concrete is the natural, simple mode of utterance; but under the influence of interest, excitement, passion, and so on, the utterance of the concrete may be greatly varied from this by means of _stress_, or force applied to some part or to all of its extent. The different variations may be described as follows: