[Note] that an utterance [is] a type of sound. An utterance is a striking of air or air being struck. For not every sound is an utterance, just as a sound coming from inanimate things like waves or winds is not an utterance.[1] But an utterance is a sound of an animate being, even though not every sound of an animate being is an utterance. Neither clapping the hands nor clearing one's throat or coughing [is an utterance]. For an utterance is a sound of an animate being, made by means of the vocal parts,[2] such as the sounds made by the lungs and the respiratory parts: both the rough artery and the windpipe.[3] And [an utterance] is not made when a sound is produced by these things in just any manner. That is why it is said that the one who is coughing does not make an utterance. However, when these things are set in motion accompanied by a bodily representation,[4] then, the sound produced by these is called an utterance. [...] The following three things are observed with regard to human utterance: (i) rhythm, (ii) harmony, (iii) diction. (i) Rhythm is concerned with time (long or short) of pronunciation.[5] For this reason, among vowels [fwnhe/nta], those that are uttered for more time are also denominated long, while those that are uttered for less time are called short. And the appropriate rhythm of words arises from the mutual composition of these things. (ii) Harmony is concerned with symmetry of the high and the low [pitch]. (iii) Diction is concerned with the configuration of syllables, by which the concept of the spoken things is signified. Now since human utterance has these things in a proper sense, but musical instruments also in a certain sense imitate them, because of this they also are said by analogy to make utterance.
[Note] that they[6] distinguish utterance from sound in two ways: by the mode of its generation and by its purpose. Now by the mode of its generation because utterance arises when the inhaled air is squeezed out by a contraction of the chest according to the psychic power inherent in it and falls upon the rough artery and the air enclosed in it. Such air rebounding at one stroke continually hits the adjacent air, reaching the hearing. For the empty part of the mouth up to the root of the tongue is the windpipe. From that place two cavities extend: the one, which is also called artery, toward the chest; the other in the sinew, which is called gullet [oi)sofa/gos], as well. [...] And the passing of the breath occurs through the rough artery, and such a passing happens both in inhaling and exhalation, which produces, according to the aforesaid mode, when it is breathed out a sound that is called utterance when it arises accompanied by a significant representation. Thus by the mode of its generation utterance differs from sounds in this fashion. [...] By the mode of its purpose [utterance differs from sound] because utterance arises from an impulse of the animal and connotes something. For that reason such an utterance is accompanied by a representation as well. Therefore, the sounds of the irrational animals are also utterances. [...] For a dog, when it has an impression of someone alien to it, barks, and when it has an impression of someone familiar to it, fawns. In the same way for the other animals also, utterances signify the psychic faculties and dispositions. For while desiring food or any other thing, they make use of utterance.