Timing and sequencing in consonants and vowels.

Conventional alphabetic transcriptions such as

ElIf@nt

tend to coerce us into imagining that the individual consonants and vowels are put together in a simple sequence in time, like this:
   
E l
 I f
 @ n
 t
time --->

But this is probably not right. The phenomena of Consonant-Vowel coarticulation and Vowel-Vowel coarticulation suggest that something else is going on.

Vowel-to-Vowel coarticulation

For example: the central vowels in "to the" are often slightly different in e.g. "go to the park" vs. "go to the pictures":

g@Ut@ð@p'A:k   vs.   g@UtÏðÏp'IktS@z

The vowels in "to the" are a bit higher before a close vowel than before an open vowel. It is as if the stressed vowels exert an influence over the preceding unstressed vowels. This influence has no trouble going past or through any intervening consonants:
   

@ <---
 @ <---
 'A:
vs.

Ï <---
 Ï <---
 'I
t
ð
p
k
t
ð
p
k

The Swedish phonetician Sven Öhman demonstrated in the mid 1960's that in nonsense Vowel1 + Consonant + Vowel2 sequences spoken by Swedish, English and Russian speakers, Vowel1varies according to the identity of Vowel2. In some cases where Vowel1was unrounded and Vowel2 was rounded, he observed that the lips sometimes began to move into the rounded position ready for the rounded articulation of the Vowel2 during the articulation of Vowel1. In consequence, the intervening consonant was also lip-rounded (as you would expect for a consonant before a rounded vowel, but here we begin to see an explanation for that fact.)This suggests a timing pattern like this (for e.g. [igu]):


i
 rounding
<----------
u

g

Öhman (1966) wrote:

Since traces of the final vowel are observable already in the transition from the initial vowel to the consonant, it must be concluded that a motion toward the final vowel starts not much later than, or perhaps even simultaneously with, the onset of the stop-consonant gesture. A VCV utterance of the kind studied here can, accordingly, not be regarded as a linear sequence of three successive gestures. We have clear evidence that the stop-consonant gestures are actually superimposed on a context-dependent vowel substrate that is present during all of the consonantal gesture.

This model is often known as the co-production model of consonant-vowel timing, since it holds that consonants and vowels are produced at the same time by two separate, parallel, interacting processes of articulation.

Stages in the formation of stops.

Looking more closely at the fine temporal structure of (say) an intervocalic voiceless aspirated stop (e.g. the medial [t] of city), various phoneticians have identified a number of sequential stages in their production (see e.g. Abercrombie 1967 chapter 9; Ashby and Maidment 2005 pp. 56, 93-5, 126).

    Degree of aperture in the oral passage:
       >-------<  «
       1    2   3  4

In (1), the closing stage, the active articulator moves away from its position during the vowel towards its position for the stop. In (2), the holding (closure) stage, the active articulator is held against the passive articulator. In (3), the release stage, the active articulator moves away from the passive articulator and the stricture of complete closure is opened up. In (4), the plosion stage, the turbulent airflow of an aspirated stop occurs.

Not all stops in all contexts have all these phases or stages (e.g. unaspirated stops, unreleased stops etc.). In "incomplete" plosives, such as the first stops in clusters such as "apt, apter, act, actor" there are two overlapping closing and holding phases, but only the second stop is released:

    a >---k---<       
       1    2   3
          >---t------<  h«   @
          1    2       3  4

Aspiration (or its absence) is not the only type of stop release. We also encounter, in various languages:

References

Abercrombie, D. (1967) Elements of General Phonetics. Edinburgh University Press.

Öhman, S. E. G. (1966) Coarticulation in VCV Utterances: Spectrographic Measurements. Journal of the Acoustical Society of America 39, 151-68.