A plosive is a consonant articulation with the following characteristics:
Two articulators form a stricture that allows no air to escape from the vocal tract (CLOSURE PHASE)
The air behind the obstruction becomes compressed (HOLD PHASE)
The obstruction is released, air escapes and may produce a sound – plosion (RELEASE PHASE)
There may be voicing during part or all of the plosive articulation (post-release phase)
Voiced vs voiceless stops
Voicing usually starts just before the release phase
In careful speech, there may be voicing during the entire hold phase (the plosive is fully voiced)
In rapid speech there may be no voicing at all (!)
The release is followed by an audible plosion – a burst of noise – aspiration
Then the vocal cords come together and voicing begins for the following vowel
The most important difference between voiced and voiceless stops is therefore aspiration
If English speakers hear a fully voiced initial plosive, they will hear it as b, d, or g, but will notice that it does not sound quite natural.
If they hear a voiceless unaspirated plosive, they will also hear that as one of b, d, g, because it is aspiration, not voicing, which distinguishes initial p, t, k from b, d, g.
Only when they hear a voiceless aspirated plosive, will they hear is as one of p, t, k; experiments have shown that we perceive aspiration when there is a delay between the sound of plosion and the beginning (or onset) of voicing.
FORCE OF ARTICULATION
/b, d, g/ are called voiced plosives, although the above description makes it clear that it is not very accurate to call them “voiced”.
Some phoneticians say that /p, t, k/ are produced with more force than /b, d, g/,
So, the voiceless plosives /p, t, k/ are sometimes called fortis (meaning “strong”), and /b, d, g/ are called lenis (meaning "weak")
Final voiced obstruents do not occur in Polish – final devoicing
Some final notes...
Voiceless stops and affricates /p, t, k, t∫/ are longer than the corresponding voiced stops and affricates /b, d, g, „dż”/ when at the end of a syllable
Voiceless stops /p, t, k/ are unaspirated in words such as „spew, stew, skew”
In many accents of English, syllable final /p, t, k/ are accompanied by a glottal stop, as in pronunciations of „tip, pit, kick” /tI”?”p. pI”?”t, kI”?”k/
NASALS – air escapes through the nose – soft palate must be lowered; compare (buy, my):
can be syllabic, e.g. button, cotton
/m, n/ occur freely
/ŋ/ never occurs initially – usually word-finally or medially: in monomorphemic words and grading adjectives we have /ŋg/, e.g. finger, anger, longer; in bimorphemic words we have /ŋ/, e.g. sing|er, hang|er, he long|s for sth.
/ŋ/ can be preceded only by /I, e, æ, υ (less rounded), ∂, a, o/