Coarticulation and Speech Target Undershoot: A Dynamic…

What Coarticulation Is

Coarticulation refers to the phenomenon where sounds are produced with overlapping articulatory movements. In rapid speech, one sound's articulation begins before another ends, leading to a blending of phonemes. This blending can cause target undershoot, where the tongue or lips overshoot their intended position for the next sound.

The concept is fundamental in phonetics and has implications for both speech production and perception.

Modeling Coarticulation

A task-dynamics model of coarticulation uses a critically-damped mass-spring system to simulate the movement of an articulator, such as the tongue. This model captures how the articulator responds to a sequence of vowel targets at different speech rates.

The model includes parameters like stiffness (omega) and damping ratio (zeta), which affect the speed and smoothness of the articulatory movements.

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Why It Matters

Understanding coarticulation is essential for designing speech synthesis systems, improving hearing aids, and developing assistive technologies that aid in communication. It also helps linguists and phoneticians better understand the complexities of human speech production.

Research into coarticulation can lead to more natural-sounding speech in artificial voices and better algorithms for automatic speech recognition.

Real-World Examples

In everyday speech, coarticulation is evident when saying words like 'butter' or 'knight.' The rapid transition between sounds causes the tongue to overshoot its target position for the next sound.

Studying coarticulation can also help in diagnosing and treating speech disorders, such as dysarthria, by providing insights into abnormal articulatory movements.

Frequently asked questions

What causes undershoot during coarticulation?

Undershoot occurs because the articulator begins moving towards a new target before fully reaching the previous one. This is due to the rapid transition between sounds in speech, leading to an overshooting of the intended position.

How does increasing the speech rate affect coarticulation?

Increasing the speech rate generally increases undershoot because there's less time for the articulator to reach its target before moving on to the next sound. This can be observed in the model by adjusting the speech rate slider.

What role does stiffness (omega) play in coarticulation?

Stiffness affects how quickly and forcefully the articulator responds to changes in target positions. Higher stiffness results in faster, more direct movements towards targets, which can reduce undershoot but may also make speech less smooth.

Why is damping ratio (zeta) important?

The damping ratio influences how quickly the articulator settles into its new position after overshooting. A higher damping ratio means a more gradual settling, which can help in reducing undershoot and improving speech clarity.

Try it live

Everything above runs in your browser — open Coarticulation & Speech Target Undershoot and change the parameters while it is running. Nothing is installed, nothing is uploaded, the whole model lives in one tab.

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Coarticulation and Speech Target Undershoot: A Dynamic Model of Vocal Tract Movement