(Semaan's translation of above text:)
Second Chapter
On the Cause of the Formation of the Speech-Sounds
It is the vibration itself that produces sound. The state the vibration itself is in, i.e., the continuity of its parts, its evenness, or unevenness, and its branching, produce the acuteness and the density (of the sound). The first two (namely, the continuity and evenness) cause the acuteness, the other two, the density.
It is the state in which the vibration is, by reason of the forms imposed upon it by the various exits and distractions, that forms (each particular) speech-sound, for a speech-sound is an accidental form of sound audibly distinguishable from another sound that has similar acuteness and density.
In reality, some speech-sounds are simple entities whose formation is the result of complete obstruction of the sound, or of the air which produces the sound, followed by a release impulsion. Others are complex entities produced by incomplete obstruction (of the air) though with release...
First sentence as read by a synthetic actor. (AVI / MOV)
Semaan, K. H. (1963) Arabic Phonetics.