Vowel Sound Shift and the Portuguese of the Azores
For some linguists, the area of origin of the pioneering settlers remains an important factor that must be taken into consideration when examining regional linguistic variations. As Raven McDavid (1980:19) points out: "Evidence accumulated in Germany, France, and Italy revealed that in Europe regional speech differences are related to historical forces: original settlements, routes of migration, older political boundaries, and centers of cultural diffusion." In the case of the Azores, the information available, though not conclusive, would seem to suggest a southern Portuguese component in the early settlement of the islands, primarily in São Miguel. As such, the linguistic legacy from mainland Portugal ought to be recognized as constituting the predominant factor in regard to the foundation of the Azorean speech. This language continued its process of natural and spontaneous phonetic evolution, thus giving rise to its distinctive phonological characteristics (Blayer 2003, 2005, 2007).
The presence of the palatal sounds, [ü]and [ö], in the vocalic system of São Miguel has been discussed as largely due to the working of Celtic substratum influences, explained by a possible French settlement in the village of Bretanha. Any attempt to argue an external influence for the presence of the palatal vocalic sounds in the speech of the Azores has only been claimed on the basis that this phenomenon is reflected in the speech community of one area. Furthermore, in most linguistic studies on the Portuguese language, the barest mention of other islands, as well as other Portuguese-speaking areas where these sounds are prevalent, has been scarcely recorded.
To explain the presence of [ü] in Romance as a Celtic connection, is according to Posner (1980:238) "somewhat tenuous, especially as we know little about Gaulish Celtic [...] We have little hard evidence about persistence of Gaulish, nor indeed of the widespread use of Celtic throughout Roman Gaul." With reference to São Miguel, it is not possible to conclusively posit interference of the speech pattern of Bretanha on that of São Miguel, nor trace a Celto-French contribution to the speech of this village. It is important to insist upon the fact that the settlement of the Azores was primarily of Portuguese origin, thus negating the probability that a foreign linguistic presence played a role in 'phonological' development. While some of the arguments are questionable regarding the Celto-French interference, and given the scarcity of documentary evidence seeking to locate the causes of sound changes in Romance by means of an external factor, Jungeman maintains that to identify substratum influence in phonology some conditions should be fulfilled: (1) the internal factors alone may not explain the presence of the palatal sounds in; (2) there should have existed characteristics with a direct or indirect relationship with this phenomenon, (3) was there a period of bilingualism in which the two languages influenced each other; and during this time was this community completely isolated from other external influences - such as the other ethnic forces? (1955:418).
The interpretation of this phenomenon in phonological terms leads us to note that the hypothesis postulated by structuralists (Haudricourt-Juilland 1949:100-113, Martinet 1955:52-3) to explain the presence of the rounded mid-high fronted and back vowels, as well the change ü > U in Romance, is that the appearance of ü < U can be seen as a reduction of a Mehrlautphoneme ui, as a result of a displacement of back vowels. Due to asymmetry in the articulatory space available at the front and back of the mouth when [o] in checked syllables became [u], the functional load of [u] < Latin U and Romance [o] became excessive and U acquired a palatalizing articulation. The resulting vowel acted as a catalyst for the formation of the parallel phoneme /ö/. On the basis of linguistic economy, Martinet (1955) explains that everything concerning language must be viewed from "the point of view of function" -languages prefer symmetrical phonological systems and the function of sound shifts is to bring symmetry into an otherwise asymmetrical system -. Posner argues that "On the whole the structuralist ideas about symmetrical systems, casesvides, functional loads and push and drag chains are currently unfashionable [...]. However, certain sound shifts can conceivably be seen as consequent on others, where potentially pathological phonological mergers threaten." (1996:161). Spence (1972: 302), on the other hand, argues that "If we are to admit the desire for symmetry as an important factor in the process of change, it seems more plausible to see a re-organization of the system as a sort of therapeutic reaction to phonemic splits or mergers which have as it were 'slipped under the guard' of the users of the system: a move towards the re-establishment of symmetry implies that an asymmetry has arisen." Furhermore, he explains that the changes which formed the Romance vowel systems cannot be explained by systemic pressures with totally predictable results, since they led to different norms in different areas.
In light of the fact that vocalic phonological variants in other areas of the insular speech share similar tendencies (Blayer 1992), we are left wondering if the external and foreign causes were really responsible for their alleged results in São Miguel. Hence, an attempt to explain phonological changes with competing vowel systems in Romance may well prove to be more solid.