The _Voice_ therefore, as it is the _Voice_, is generated in the _Cartilages of the Wind-pipe_, then afterwards is formed into such or such _Letters_; but that it may become a lovely _Voice_, it's requisite, that those Cartilages be _smooth_, and _lined with no mucous Matter_, else the _Voice_ will become Hoarse, and sometimes be utterly lost, viz. when they have lost their Springy power.
For _Pipes_; and other _Wind-Instruments_ do most notably explain to us the nature of the _Voice_; for in them we see a certain _Voice_ or _Sound_ to be generated out of Simple Air, whilst it is as it were, rent in pieces, and forced into a tremulous Motion: Now, that in these Instruments there is a little Tongue; or which is instead of a Tongue, the same in a Man is the _Epiglott_, or Cover of the _Wind-pipe_, and the _Uvula_, or Pallate of the Mouth; but the rest of the _Cartilages_ of the _Throat_, besides that, they contribute much to the making of the _Voice_, yet are they chiefly serviceable to it, in rendering it to be more flat, and more sharp, and that especially by the _Bone of the Tongue_, and the adjoyning Muscles: But I am unwilling to put from this Office the Muscles which are proper to the _Wind-pipe_; for they all unanimously conspire to make the _Cleft of the Throat_ either wider, or narrower. But above all, here is that wonderful Faculty of modifying the _Voice_, according to Will and Pleasure; which, even as _Speech_ also, is not natural to us, but a Habite, contracted by long Use or Custom. Hence it is, that the Unskilful are not only Ignorant how to Sing, but also cannot so much as imitate others who are Singing; so also such as are ignorant of any Language, do not only not understand others who are speaking that Language, but also do not know how presently to repeat that _Voice_ which they received by their Ears.
Things principally requisite to the _Voice_, are, that the _Wind-pipe_, the former thereof be solid, dry, and of the nature of _Resounding_ Bodies. By this _Hypothesis_, two of the most Eminent _Phænomena's of the Voice_ are discovered; why the _Voice_ should then at length become firm and ripe, when the Bones have attained unto their full Strength, and due Hardness, which cometh to pass much about the Years of ripe age, when the vital Heat, doth in a greater degree exert itself: The other Phænomenon is _Hoarsness_ or an utter loss of the _Voice_, which is, when the _Cartilages_, or _Gristles of the Throat_, especially the _Epiglott_, or Coverlid of the _Wind-pipe_, is lined or besmeared all over with a slimy Viscosity, whereby they lose their _Elasticity_, or Springiness. Now these Symptoms of the _Voice_ are also common to other _Wind-instruments_, when they become too much moistned by any vapourous wetting Air. The same reason also is to be assigned why the _Voice_ doth at last quite cease in those who have made too long Harrangues, in speaking, and whose Jaws are quite dried with an immoderate Heat; for in both these cases the top of the _Wind-pipe_ is covered over with a clammy _Tenacious Phlegm_.