Introduction
This web page presents an introduction to the gesture in Articulatory Phonology and interactive apps to play around with some of the parameters of the gesture.
Words as gestural scores
In Articulatory Phonology, an articulatory gesture is seen as the basic building block of phonology. Multiple gestures are organized in gestural scores to form words. It is important to note that these gestural scores are seen as phonologoical. This means lexical entries are represented as structures of gestures rather than as string of segments. This image shows the gestural scores for "mad" and "ban". Each block represents the interval in which a gesture is active:
[Gestural scores adapted from Goldstein, Louis, Hosung Nam, Elliot L. Saltzman & Ioana Chitoran. 2009. Coupled oscillator planning model of speech timing and syllable structure. In G. Fant, H. Fujisaki & J. Shen (eds.), Frontiers in phonetics and speech science, 239–250. The Commercial Press Beijing.]
Both words have an alveolar closure in the tongue tip and a closure of the lips. They also have the same vowel gesture in the tongue body. The timing of velum opening (velum: wide) makes the difference between the two words, as it comes early in "mad" and late in "ban".
Gestures as dynamical systems
Each gesture is modelled as a dynamical system. For now, it is enough to understand that a dynamical system is a system that changes its state over time. Articulatory phonology adapted the idea of a mass-spring system as the basis for the gesture. Mass-spring systems are well-studied dynamical systems in physics and they are able to model a variety of phenomena. An animation of such a system is shown in the next image:
[Animation from wikimedia commons, user Svjo.]
In this system, a mass is attached to a spring. When you pull on the mass, the spring will be stretched. When you release the mass, the mass will be pulled back by the spring. Usually, we observe that a mass-spring system oscillates for some time until it eventually comes to rest. This is, of course, not what we observe with articulatory movements! Our articulators do not oscillate. Instead, they go immediately to a specific location. For example, the tongue moves to a constriction location at the alveolar ridge.
To model this behavior, the mass-spring system used in Articulatory Phonology is critically damped. Damping occurs everywhere in the world around us. A pendulum, for instance, swings for some time during which the amplitudes of the movement increase. Eventually it comes to a halt. In the case of critical damping, the damping is even stronger. This means that the mass will not oscillate but instead go immediately to its resting position. This resting position is often called attractor or target of the gesture.
The next image illustrates this behavior. It shows the position of a gesture over time. We could imagine this gesture representing the lip opening movement as we produce the syllable [ba].
Gestures can have different targets as shown in this illustration:
We will not go into the details of the mathematics that define the gesture but we will explore some of the factors that shape the gesture. One of these factors we will look at is the duration of the interval in which an a gesture is active. The other factor is the target of the gesture, i.e., the attractor that the gesture converges to. In the following sections, you will be able to try out the consequences of changing these parameters yourself.