Intensity may be applied alike to the voice and to sound.  The voice is strong or weak, according to the mechanism of the acoustic apparatus.  The strength or weakness of sound depends upon the speaker, who from the same apparatus evolves tones more or less strong.  It is the forte, piano and pianissimo in music.  Thus a loud voice can render weak tones, and a weak voice loud tones.  Hence the tones of both are capable of increase or diminution.

Means of Augmenting the Timbre of the Voice.

1.  A stronger voice may be obtained by taking position not upon the heel or flat of the foot, but upon the ball near the toes—­that attitude which further on we shall designate as the third.  The chest is eccentric; that is, convex and dilated.  In this position all the muscles are tense and resemble the chords of an instrument whose resonance is proportional to their tension.

2.  There are three modes of developing the voice.  A voice may be manufactured.  A natural voice is almost always more or less changed by a thousand deleterious influences.

1. In volume, by lowering the larynx, elevating the soft-palate and hollowing the tongue.

2. In intensity.—­A loud voice may be hollow.  It must be rendered deep, forcible and brilliant by these three methods:  profound inspiration, explosion and expulsion.  The intensity of an effect may depend upon expulsion or an elastic movement.  Tenuity is elasticity.  It is the rarest and yet the most essential quality of diction.

3. In compass.—­There are three ways of increasing the compass of the voice: 

  1.  By the determination of its pitch;
  2.  By practicing the vocal scale;
  3.  By the fusion of the registers upon the key-note.

The first of these methods is most effective.  The second consists in exercising upon those notes which are near the key-note.  Upon this exercise depends in great measure the homogeneity of the voice.  Taking la for the diapason, the voice which extends from the lowest notes to upper re is the chest-voice, since it suffers no acoustic modification.  From mi to la the voice is modified; it is the medium voice, or the second register, which gives full and supple tones.  The head or throat-voice, or the third register, extends from si to the highest and sharpest notes.  Its tones are weak, and should be avoided as much as possible.  There are then only four good notes—­those from mi to la, upon which the voice should be exercised.  By uniting the registers, an artificial, homogeneous voice may be created, whose tones are produced without compression and without difficulty.  This being done, it is evident that every note of the voice must successively indicate the three registers—­that is, it must be rendered in the chest, medium and head voices.

There is also a method of diminishing the voice.  As the tone is in proportion to the volume of air in the lungs, it may be weakened by contracting the epiglottis or by suppressing the respiration.