Dispersion Theory concerns the constraints that govern contrasts, the phonetic differences that can distinguish words in a language. Specifically it posits that there are distinctiveness constraints that favor contrasts that are more perceptually distinct over less distinct contrasts. The preference for distinct contrasts is hypothesized to follow from a preference to minimize perceptual confusion: In order to recover what a speaker is saying, a listener must identify the words in the utterance. The more confusable words are, the more likely a listener is to make errors. Because contrasts are the minimal permissible differences between words in a language, banning indistinct contrasts reduces the likelihood of misperception. The term ‘dispersion’ refers to the separation of sounds in perceptual space that results from maximizing the perceptual distinctiveness of the contrasts between those sounds, and is adopted from Lindblom’s Theory of Adaptive Dispersion, a theory of phoneme inventories according to which inventories are selected so as to maximize the perceptual differences between phonemes. These proposals follow a long tradition of explaining cross-linguistic tendencies in the phonetic and phonological form of languages in terms of a preference for perceptually distinct contrasts. Flemming proposes that distinctiveness constraints constitute one class of constraints in an Optimality Theoretic model of phonology. In this context, distinctiveness constraints predict several basic phenomena, the first of which is the preference for maximal dispersion in inventories of contrasting sounds that first motivated the development of the Theory of Adaptive Dispersion. But distinctiveness constraints are formulated as constraints on the surface forms of possible words that interact with other phonological constraints, so they evaluate the distinctiveness of contrasts in context. As a result, Dispersion Theory predicts that contrasts can be neutralized or enhanced in particular phonological contexts. This prediction arises because the phonetic realization of sounds depends on their context, so the perceptual differences between contrasting sounds also depend on context. If the realization of a contrast in a particular context would be insufficiently distinct (i.e., it would violate a high-ranked distinctiveness constraint), there are two options: the offending contrast can be neutralized, or it can be modified (‘enhanced’) to make it more distinct. A basic open question regarding Dispersion Theory concerns the proper formulation of distinctiveness constraints and the extent of variation in their rankings across languages, issues that are tied up with the questions about the nature of perceptual distinctiveness. Another concerns the size and nature of the comparison set of contrasting word-forms required to be able to evaluate whether a candidate output satisfies distinctiveness constraints.
The term consonant harmony refers to a class of systematic sound patterns, in which consonants interact in some assimilatory way even though they are not adjacent to each other in the word. Such long-distance assimilation can sometimes hold across a significant stretch of intervening vowels and consonants, such as in Samala (Ineseño Chumash) /s-am-net-in-waʃ/ → [ʃamnetiniwaʃ] “they did it to you”, where the alveolar sibilant /s‑/ of the 3.sbj prefix assimilates to the postalveolar sibilant /ʃ/ of the past suffix /‑waʃ/ across several intervening syllables that contain a variety of non-sibilant consonants. While consonant harmony most frequently involves coronal-specific contrasts, like in the Samala case, there are numerous cases of assimilation in other phonological properties, such as laryngeal features, nasality, secondary articulation, and even constriction degree. Not all cases of consonant harmony result in overt alternations, like the [s] ∼ [ʃ] alternation in the Samala 3.sbj prefix. Sometimes the harmony is merely a phonotactic restriction on the shape of morphemes (roots) within the lexicon. Consonant harmony tends to implicate only some group (natural class) of consonants that already share a number of features, and are hence relatively similar, while ignoring less similar consonants. The distance between the potentially interacting consonants can also play a role. For example, in many cases assimilation is limited to relatively short-distance ‘transvocalic’ contexts (. . . CVC. . . ), though the interpretation of such locality restrictions remains a matter of debate. Consonants that do not directly participate in the harmony (as triggers or undergoers of assimilation) are typically neutral and transparent, allowing the assimilating property to be propagated across them. However, this is not universally true; in recent years several cases have come to light in which certain segments can act as blockers when they intervene between a potential trigger-target pair. The main significance of consonant harmony for linguistic theory lies in its apparently non-local character and the challenges that this poses for theories of phonological representations and processes, as well as for formal models of phonological learning. Along with other types of long-distance dependencies in segmental phonology (e.g., long-distance dissimilation, and vowel harmony systems with one or more transparent vowels), sound patterns of consonant harmony have contributed to the development of many theoretical constructs, such as autosegmental (nonlinear) representations, feature geometry, underspecification, feature spreading, strict locality (vs. ‘gapped’ representations), parametrized visibility, agreement constraints, and surface correspondence relations. The formal analysis of long-distance assimilation (and dissimilation) remains a rich and vibrant area of theoretical research. The empirical base for such theoretical inquiry also continues to be expanded. On the one hand, previously undocumented cases (or new, surprising details of known cases) continue to be added to the corpus of attested consonant harmony patterns. On the other hand, artificial phonology learning experiments allow the properties of typologically rare or unattested patterns to be explored in a controlled laboratory setting.
Blending is a type of word formation in which two or more words are merged into one so that the blended constituents are either clipped, or partially overlap. An example of a typical blend is brunch, in which the beginning of the word breakfast is joined with the ending of the word lunch. In many cases such as motel (motor + hotel) or blizzaster (blizzard + disaster) the constituents of a blend overlap at segments that are phonologically or graphically identical. In some blends, both constituents retain their form as a result of overlap, for example, stoption (stop + option). These examples illustrate only a handful of the variety of forms blends may take; more exotic examples include formations like Thankshallowistmas (Thanksgiving + Halloween + Christmas). The visual and audial amalgamation in blends is reflected on the semantic level. It is common to form blends meaning a combination or a product of two objects or phenomena, such as an animal breed (e.g., zorse, a breed of zebra and horse), an interlanguage variety (e.g., franglais, which is a French blend of français and anglais meaning a mixture of French and English languages), or other type of mix (e.g., a shress is a type of clothes having features of both a shirt and a dress). Blending as a word formation process can be regarded as a subtype of compounding because, like compounds, blends are formed of two (or sometimes more) content words and semantically either are hyponyms of one of their constituents, or exhibit some kind of paradigmatic relationships between the constituents. In contrast to compounds, however, the formation of blends is restricted by a number of phonological constraints given that the resulting formation is a single word. In particular, blends tend to be of the same length as the longest of their constituent words, and to preserve the main stress of one of their constituents. Certain regularities are also observed in terms of ordering of the words in a blend (e.g., shorter first, more frequent first), and in the position of the switch point, that is, where one blended word is cut off and switched to another (typically at the syllable boundary or at the onset/rime boundary). The regularities of blend formation can be related to the recognizability of the blended words.