Book 11
1.20
Further, the throat must be sound, that is to say, soft and smooth; for if the throat be unsound, the voice is broken or dulled or becomes harsh or squeaky. For just as the sound produced in the pipe by the same volume of breath varies according as the stops are closed or open, or the instrument is clogged or cracked, so the voice is strangled if the throat be swollen, and muffled if it is obstructed, while it becomes rasping if the throat is inflamed, and may be compared to an organ with broken pipes in cases where the throat is subject to spasms.
1.21
Again, the presence of some obstacle may divide the breath just as a pebble will divide shallow waters, which, although their currents unite again soon after the obstruction is past, still leave a hollow space in rear of the object struck. An excess of moisture also impedes the voice, while a deficiency weakens it. As regards fatigue, its effect is the same as upon the body: it affects the voice not merely at the moment of speaking, but for some time afterwards.
1.22
But while exercise, which gives strength in all cases, is equally necessary both for orators and singing-masters, it is a different kind of exercise which they require. For the orator is too much occupied by civil affairs to be able to allot fixed times for taking a walk, and he cannot tune his voice through all the notes of the scale nor spare it exertion, since it is frequently necessary for him to speak in several cases in succession.
