Gestures and their consequences

Gestures are actions that result in certain articulatory, aerodynamic and acoustic consequences.

The consequences of a given action may vary as a function of conditions in the vocal tract which the particular gesture does not itself control.

For example: "miss you"

Variability of consequences is particularly signficant for laryngeal gestures.

 

Vocal Fold Vibration

Requires two sets of conditions to be met:

• aerodynamic conditions
  pressure below the glottis must be greater than pressure above the glottis.

• laryngeal conditions
  Vocal folds must be narrowed,
  Vocal folds cannot be too stiff.

Laryngeal gestures

Gesture	Expected Consequences
vocal fold narrowing	voicing
vocal fold separation	devoicing

Laryngeal gestures will not always have the expected consequences, if the proper aerodynamic condition are not met.

In such circumstances, what counts, in terms of contrast, actions or their consequences?

Voicing during stop closures

Problematic context for voicing

Supralaryngeal cavity is closed off.

Within 15 ms, pressure above glottis will exceed than in lungs, and vibration will cease (unless something else happens).

Try maintaining voicing during closure, and you will see that you can only do it for a short amount of time.

 

Voiced Stops in English

They often lack any voicing during the closure interval.

Should be transcribed as voiceless unaspirated stops.

However, data on laryngeal gestures show that the same laryngeal gesture (vocal fold narrowing) occurs in English "voiced" stops, regardless of whether vibration actually occurs.

Sometimes the laryngeal gesture has the expected consequence, sometimes it does not.

But we hear both cases as "voiced", indicating that it is the action, not the consequences, that is important for contrast in this case.

 

Voicing in Thai stops

 

In Thai, stops with voicing throughout their closures contrast with stops that lack voicing during their closures.

Unlike English, these cases are produced with different gestures in Thai:

Voiceless unaspirated stops
Laryngeal gestures separate the vocal folds

voiced stops
no laryngeal separation

But how do they manage to sustain voicing during closures for the voiced stops?

 

Supralaryngeal Expansion

 

One way to sustain voicing during a closure is to expand the supralaryngeal cavity, so as to lower the pressure that builds up.

 

How can the cavity be expanded, while maintaining closure?

 

Passive Expansion

 

Soft tissues of supralaryngeal cavity will compress passively as pressure builds up, thus expanding the cavity size.

 

Effectiveness of compression:

labial stops > coronal stops > dorsal stops

 

This accounts for differences in stop inventories in languages, and "gaps" in the systems.

e.g., Thai lacks a voiced dorsal stop

 

Active Expansion

 

Probably required in a language that contrasts voiced and voiceless unaspirated stops.

Larynx lowering is also the basic gesture employed for expansion.

 

 

Voiced Implosives

 

Voiced implosives use the larynx lowering technique to rapidly expand the size of the supralaryngeal cavity, and to create strong vocal fold vibration.

Timing of larynx lowering with respect to release of oral constriction differs from that in voiced (pulmonic) stops.

[baba]	[a a]

Can contrast with plosives in various languages.

Sindhi