Let us look in more detail at phonation first. Phonation describes whether a sound is voiceless or voiced or, more generally, it describes all the means by which the larynx functions as a source of sound. Phonation really is the single most important function of the larynx as a sound source. There are basically six modes of phonation.
voiceless : absence of any vocal fold vibration
vocal folds far enough apart to allow a laminar (= non-turbulent) airflow through the glottis
voiced : normal vocal fold vibration occuring along most or all of the length of the glottis
aspiration : glottis is open (cf. voicelessness), but moves towards closure of larynx
closing movement causes aspirated sound
Manners of articulation
Clark and Yallop use two features to describe the manner of articulation of consonants: constriction and articulation.
The degree of constriction decreases from total closure via partial constriction
to a fully open vowel like manner.
Articulation divides into dynamic and stable.
Altogether, there are seven recognized manners of articulation: stop, fricative, approximant, nasal, flap, tap and trill.
: The manners of articulation are described as follows
Stop : formation and rapid release of a complete closure at any point
in the vocal tract from the glottis to the lips, dynamic articulation (e.g. egressive pulmonic stops: plosives)
Fricative : potentially stable articulation produced by a constriction
in the vocal tract that is narrow enough to create a turbulent airflow
Approximant : potentially stable articulation in which the constriction
is normally greater than in a vowel but not great enough to produce turbulence at the point of constriction
Nasal : stoppage at some point in the oral cavity, velum is lowered to
allow airflow through the nasal cavity, stable articulation
Tap : dynamic articulation where there is a brief occlusion in the vocal tract,
a single deliberate movement to create a closure, equivalent to a very short stop
Flap : dynamic articulation where there is a brief occlusion in the vocal tract,
one articulator strikes the other in passing not so much to create a brief closure
but more as the incidental effect of the articulatory gesture
Trill : a dynamic articulation produced by the vibration of any articulator, a series of vibrations