Articulation is the utterance of the elementary sounds of a language, and
of their combinations.
An Elementary Sound is a simple, distinct sound made by the organs of
speech.
The Elementary Sounds of the English language are divided into Vocals,
Subvocals, and Aspirates.
Vocals are those sounds which consist of pure tone only. They are the most
prominent elements of speech. A diphthong is a union of two vocals,
commencing with one and ending with the other.
Subvocals are those sounds in which the vocalized breath is more or less
obstructed.
Aspirates consist of breath only, modified by the vocal organs.