Title of the article

2.The prosodic hierarchy of words

The prosodic hierarchy up to the word level consists of four constituents. The lowest element of the prosodic hierarchy is the mora (). Since there are often no segmental slots in moraic models, the mora has a double function as the unit of syllable weight and as the unique sub-syllabic constituent. The moraic level is dominated by the syllabic level (), and syllables are parsed into feet (F) at the foot level above. The highest unit is the prosodic word (Wd) which directly dominates the foot level (see Figure 1):

Prosodic word (Wd)

Foot (F)

Syllable ()

Mora ()

Figure 4. The prosodic hierarchy (Selkirk, 1980)
Syllables differ with respect to the number of moras they contain. Light syllables contain one mora, while heavy syllables contain at least two. The tendency of languages to assign stress to heavy syllables is expressed by the Weight-to-Stress-Principle (WSP). In a parametric approach to word stress (cf. Hayes, 1995), languages either respect this principle (quantity-sensitive languages) or do not (quantity-insensitive languages).

The next constituent of the prosodic organization above the syllable level is the foot. Ideally, the foot is binary branching which implies that it should consist of two moras or of two syllables. Thus, a binary foot can be monosyllabic if it contains two moras (e.g.  ‘duck’) or it can be disyllabic if it consists of two syllables or two moras (e.g.  ‘papa’). The head constituent of the foot receives stress.

The prosodic word is the domain of stress application. It can also coincide with a single foot. Because the foot size is the smallest shape a prosodic word can have, it is called Minimal Word. Many languages have restrictions such that content words must not be smaller than the minimal word. There is ample evidence that the minimal word restriction also governs the shape of the early words in language acquisition (Demuth & Fee, 1995; Demuth, 1996; Fikkert, 1994; Ota, 2001).

A very important principle of the prosodic hierarchy is the Strict Layer Hypothesis (Selkirk, 1984) which demands that layers must not be skipped, i.e. that a given prosodic constituent_(n-1) is contained in the constituent_(n) immediately above. Furthermore, it requires that constituents have one and only one head, which implies that there is always a difference in prominence among the elements forming a given prosodic unit.