Confronting the European Portuguese central vowel distinction

1. The problem

Stressed syllables in European Portuguese contrast seven oral vowels, /i, u, e, o, ε, ɔ, a/, which are reduced to a simpler four-vowel set in unstressed syllables. Although /a/ never undergoes any phonological neutralization through vowel reduction, it has a raised allophone [ɐ] which occurs in several environments:

1. (1)

   1. a. In unstressed position

   2. b. In stressed position efore nasals and palatals

Despite the lack of neutralization and the predictability of /a/-raising, a number of dialects show a surface contrast between [a] and [ɐ] in stressed syllables. However, this ‘contrast’ appears only in a very limited context, namely in the first person plural between the present indicative and the past perfect indicative of /a/-theme verbs. This is because the two tenses have segmentally identical person-number suffixes [muʃ] and are distinguished on the surface only by the vowel preceding the suffix’s /m/. Few authors discuss how to analyse this distinction, and some, such as Mateus and d’Andrade (2000: 74, 77), give identical underlying forms for the relevant pairs, despite transcribing the distinction phonetically:

1. (2)

   1. a. /fal + a]_Stmos/ [fɐˈlɐmuʃ] ‘we speak’

   2. b. /fal + a]_St mos/ [fɐˈlamuʃ] ‘we spoke’

Carvalho (2004: 14, fn. 2) even explicitly sets this phenomenon aside while providing an otherwise very insightful analysis of Portuguese verbal morphophonology:

I shall leave aside the /ɐ/ ∼ /a/ opposition that exists only before heterosyllabic nasals in central [European Portuguese] for a particular morphological purpose: matamos ‘we kill’/ matámos ‘we killed’.

According to Redenbarger (1981), some scholars have proposed that examples such as (2) be dealt with by positing two separate phonemes /a/ and /ɐ/, but given the extremely limited contexts in which these surface realizations appear to be in opposition to each other, such an analysis overgenerates in terms of the presence of lexical contrasts. Nonetheless, no author to date has offered a satisfactory synchronic explanation of these facts. I will show that, by extending Carvalho’s (2004) analysis of Portuguese verbs, there is an elegant and independently motivated solution to the problem of the [a] ∼ [ɐ] contrast.

2. Timing units and height

Let us first consider the phenomenon known as crasis (Portuguese crase), exemplified in (3b). Crasis occurs when two unstressed instances of /a/ come together across a word boundary and coalesce into a single vowel. Unstressed /a/ is typically raised to [ɐ] by phonetic vowel reduction, as in (3a), but crasis blocks this process, and the un-stressed vowel is realized as [a].

1. (3) Crasis Carvalho 2011: 6, adapted)

   1. a. VR: // → [ɐ] in unstressed syllbles

   2. b. Crasis: [ɐ]+[ɐ’migɐ] → [a’migɐ]     a amiga        ‘the friend (fem)’

                    [’kazɐ]+[ɐ’zṵɫ] → [’kaza’zṵɫ]         casa azul        ‘blue house’

                    [’pagɐ]+[ɐ’kõⁿtɐ] → [’paga’kõⁿtɐ] paga a conta ‘pay the bill!’

                    [’εɾɐ]+[ɐ’li] → [’εɾa’li]                           era ali             ‘it was there’

Carvalho (2011) suggests that if, in an element-based theory, [a] is represented with two resonance elements {A, A}, and [ɐ] is represented with a single resonance element {A}, then crasis can be analysed as the combination of the elements of two instances of [ɐ], creating [a].² I have illustrated this in (4).

1. (4) Illustration of Carvalho’s 2011) analysis of crasis
   

While this approach captures the compositional aspect of coalescence, it is essentially a notational variant of the two-phoneme analysis, with phonological elements standing in for phonological features; it still needs to assume that [a] and [ɐ] have distinct phonemic representations. I propose instead that the effect of crasis results not from the composition of phonological features, but from the double-linking of skeletal positions. In other words, crasis is phonological length.

1. (5)

The analysis in (5) is preferable to that in (4) for several reasons. First, it allows us to remain agnostic about the nature of segmental representations (i.e., whether contrasts are encoded with elements, features or something else). Second, the V-slots involved in coalescence are present in the underlying forms of the unstressed vowels in noncrasis position, since segments require skeletal slots in order to be realized at all; crasis is simply the preservation of both V-slots in a position where two of them have come together.

A...