formant frequency values for control of a resonance synthesizer. Target values of articulatory parameters stored for each phone are distinguished as 'marked' or 'unmarked', depending on whether they are characteristic of the articulation of the phone; the distinction is much the same as Coker's important v. unimportant. A further distinction is made between position and closure parameters. The transition of a parameter from the midpoint of one phone to the midpoint of the next is made up of linear segments, and varies depending on the type of each phone (vowel, consonant, or pause), the marking of the two target values, the characteristic rate of each parameter, and the parameter type (position or closure). The rather complex transition rules insure that marked target values for consonant closure parameters will be attained and held, and that progress towards other marked target values will occur over a longer time and at a more rapid rate than toward unmarked values. Thus coarticulation and centralization are provided for. In general a phone can influence only the adjacent phones, but nasalization is provided for by allowing the velar closure parameter to influence several preceding phones.

Henke's (1967) model attempts to handle the same coarticulatory phenomena as Haggard's and Coker's while avoiding a commitment to a parametrization in favor of a naturalistic representation of articulation. Each articulator is represented by a family of 'fleshpoints' on the midsagittal plane. During the motion of an articulator, each point moves along a vector determined by a target location and a target articulator shape. During the early part of its motion, a point first accelerates as the inertia of the articulator is overcome, then attains an appropriate steady velocity, and finally slows as it approaches the target point. The motion of the articulators is determined by a set of attributes stored for each phone. A configurative attribute corresponds to a target location and shape; a strength attribute, to the force which moves an articulator. At any moment, motion may be controlled by attributes associated with one or several successive phones. However, different attributes referring to the same articulatory region cannot both apply at once. A change of attribute will occur at a time dependent on the attributes of the current phone and of the following phone, and upon the progress of articulatory movements determined by other attributes. For example, when articulation of a stop consonant begins, the relevant stop attributes, specifying the shape and location of the articulator and the force of the closure, assume control of the articulator. When closure is attained, the attributes of a following vowel, except those which conflict with the stop attributes, are applied, and attributes of earlier phones are dropped. After the stop is released, all the attributes of the following vowel apply for enough time to allow the articulators to approach the vowel target.

Systems such as those of Coker, Haggard and Henke are more theoretically adequate than shape systems; we are clearly closer to the level of phonetic features. The translation from discrete to continuous domains is more natural because a target is defined for each articulator. We might compare the kind of description