What effect the compression of the larynx has in articulation may be seen by comparing these pairs of consonants:

With compression.Without compression.
BP
GK
DT
ZS
Th
VF
JSh

These, as Mr. Tooke observes, differ, each from its partner, by a certain unnoticed and almost imperceptible motion or compression of or near the larynx. This compression, he remarks, the Welsh never use. For instead of

I vow by God, that Jenkin is a wizard;

they say,

I fow by Cot, that Shenkin iss a wisart.

The consonants have been distributed into different classes, according to the organs chiefly employed in their formation.

The Labial are eb, ep, ef, ev.
Dentaled, et, etħ, eth.
Palataleg, ek, el, er, ess, esh, ez, ej.
Nasalem, en, ing.

The association of two vowels, whether the sound of each be heard or not, is called a diphthong, and the concurrence of three is called a triphthong.