[…] no animal (that we know of) has any expression which he learns, which is not the direct gift of nature to him […] we have also our “natural” expression, in grimace, gesture, and tone; and we make use of it: on the one hand, for communication where the usual means is made of no avail- as between men of different tongues who by deafness are cut off from the use of the speech- and, on the other hand, for embellishing and explaining and enforcing our ordinary language […].
- Whitney (1875), a pag.282-283

[…] the tones significant of feeling, of which no one can deny the existence because they are still an important part of our expression, are fully capable of becoming the effective initiators of language.
- Whitney (1875), a pag.288

Above the vibrating reed-apparatus is set, after the fashion of a sounding box, the cavity of the pharynx, with that of the mouth, and the nasal passage; and movements of the throat and mouth-organs under voluntary control so alter the shape and size of this box as to give to the tone produced a variety of characters, or to modify it into a variety of tones- which are the sounds of our spoken alphabet.
- Whitney (1875), a pag.59

Every alphabetic system must start from the sound ‘a’ (of ‘far’, ‘father’); for this is the fundamental tone of the human voice; the purest intonated product of lungs and throat; if we open the mouth and fauces to their widest, getting out of the way everything that should modify the issuing current; this is the sound that is heard. Upon this openest tone various modifications are produced by narrowing the oral cavity, at different points and to different degrees: the less marked modifications, which, though they alter decidedly the quality of the tone, yet leave predominant the element of tone, of material, give rise to the sounds which we call vowels.
- Whitney (1875), a pag.60-61