1.1 Aspirated [s], aspirated stops in Western Andalusian Spanish, and purpose of this research

In many dialects of Spanish, in both Europe and Latin America, syllable-final /s/ is often pronounced as a period of glottal frication or breathy voicing, a phenomenon that has come to be known in the literature as /s/-aspiration (Lipski Reference Lipski1994, Hualde Reference Hualde2005). The realization of /s/-aspiration in the western variety of Andalusian Spanish studied in this article is often described as a simple replacement of [h] for syllable-final /s/, as in pasta [pahta] ‘pasta’. However, more detailed descriptions (e.g. Zamora Vicente Reference Zamora Vicente1969, Romero Reference Romero1995a, Torreira Reference Torreira, Prieto, Mascaró and Solé2007a) have noted a wider range of variation in the phonetic realization of this weakening phenomenon. In utterance-final position /s/ is generally elided: gatos [gato] ‘cats’; in word-final position before a vowel, [h] is commonly heard: los otros [lohotro] ‘the others’; in preconsonantal position, aspirated /s/ is coarticulated in different ways with the upcoming consonant: gemination is said to occur in the environment of nasals, laterals, and other fricatives: los martes [lomːarte] ‘on Tuedays’, los lunes [lolːune] ‘on Mondays’ and las flores [lafːlore] ‘the flowers’, respectively; in front of voiced stops, aspiration leads to long voiced fricatives: los gatos [loɣːato] ‘the cats’. As noted by Romero (Reference Romero and Fowler1995b), this variation indicates that the phonetic realization of /s/-aspiration in Western Andalusian Spanish (WAS) is in fact more complex than suggested by a simple segmental rule (i.e. /s/ > [h]).

This article deals with the realization of /s/-aspiration in yet another preconsonantal context, namely before a voiceless stop. Recent studies have shown that WAS aspirated /s/ plus voiceless stop clusters are realized as long voiceless stop closures variably preceded and followed by breathy voicing or aspiration (Torreira Reference Torreira, Prieto, Mascaró and Solé2007a, Reference Torreirab; O'Neill Reference O'Neill2009). This phonetic pattern is unusual in the sense that postaspirated stops have not been reported to occur in any other dialect of Spanish, and more generally because of the co-occurrence in the same stop of both pre- and postaspiration, a rare phenomenon reported in the literature only for some Nordic dialects (see e.g. Helgason & Ringen Reference Helgason and Ringen2008, for Central Standard Swedish). More particularly, we investigate whether the occurrence of postaspiration in WAS voiceless stops results from extensive coarticulation and articulatory overlap with preceding [h], as proposed in previous research (Torreira Reference Torreira, Prieto, Mascaró and Solé2007a, Reference Torreirab; Parrell Reference Parrell2012), or if it is intended by speakers as an integral part of a series of aspirated stops, distinct from the plain voiceless stop in the Spanish consonant inventory (O'Neill Reference O'Neill2009). In order to address this issue, we carried out a production experiment in which we manipulated speech rate and stress location, two factors known to condition the extent of coarticulation and the realization of segmental cues (Lindblom Reference Lindblom1963, Gay Reference Gay1981, Browman & Goldstein Reference Browman, Goldstein, Kingston and Beckman1990, Fourakis Reference Fourakis1991, Moon & Lindblom Reference Moon and Lindblom1994, Byrd & Tan Reference Byrd and Tan1996, Davidson Reference Davidson2006).

1.2 Aspirated stops in Western Andalusian Spanish

Torreira (Reference Torreira, Prieto, Mascaró and Solé2007a), the first phonetic study to our knowledge to investigate pre- and postaspirated stops in WAS, compared [h + voiceless stop] clusters in this dialect with [l + voiceless stop] clusters and intervocalic voiceless stops in the same dialect and in Castilian Spanish, and additionally, with [s + voiceless stop] clusters in Castilian Spanish. It was found that both Voice Onset Time (VOT) and stop closure durations were statistically significantly longer in Western Andalusian Spanish [h + voiceless stop] clusters than in the other two segmental sequences in the same dialect, and than in all the examined segmental sequences in Castilian Spanish. Moreover, considerable variability was found in the occurrence of breathy voicing and preaspiration in WAS stops preceded by [h]. Figures 1 and 2 illustrate the realization of aspirated /s/ plus voiceless stop clusters in Western Andalusian Spanish. The example in Figure 1 exhibits a closure preceded by a very brief period of breathy voicing, and followed by a considerable period of postaspiration (48 ms). Figure 2, on the other hand, displays clear periods of both pre- and postaspiration (79 ms).Footnote ¹

Figure 1

Word lista ‘list’ as pronounced by a speaker from Seville in Western Andalusia (Spain).

Figure 2

Word cascó ‘cracked’ as pronounced by a speaker from Cádiz in Western Andalusia (Spain).

In a follow-up study, Torreira (Reference Torreira2007b) compared Western Andalusian and two other [s]-aspirating dialects: Argentinean and Puerto Rican Spanish. It was found that Argentinean [t] and [k] and Puerto Rican [k] had slightly longer VOT when preceded by [h] than when preceded by [l] or intervocalically. However, the VOT differences in these dialects were much smaller than those found for Western Andalusian Spanish, which, moreover, were present for all three stop types. Another difference between Andalusian Spanish and the other two dialects regarded stop closure duration. Andalusian [h + voiceless stop] clusters were characterized by longer closure durations than intervocalic stops, but no lengthening of the stop closure was found for the other dialects. Finally, it was found that the duration of preaspiration before the stop closure in [h + voiceless stop] clusters was significantly longer in Argentinean and Puerto Rican Spanish than in Western Andalusian Spanish. It was concluded that [h + voiceless stop] clusters in Western Andalusian were produced with a great deal of gestural overlap, and that speakers of Argentinean and Puerto Rican Spanish produced the segments in the clusters in a more sequential manner.

1.3 The nature of aspirated stops in Andalusian Spanish

The two studies reviewed above showed that the realization of [h + voiceless stop] clusters with long pre- and postaspirated stop closures is a dialect-specific feature of Western Andalusian, not found in all [s] aspirating varieties of Spanish. Torreira (Reference Torreira, Prieto, Mascaró and Solé2007a, Reference Torreirab) further argued that this coarticulation pattern could not be easily dealt with in segmental terms. First, the amount of overlap between the acoustic consequences of [h] and of the following stop was such that one segment could not be properly said to precede the other. Second, the differences in the timing of oral and glottal gestures found between Western Andalusian Spanish and Argentinean and Puerto Rican Spanish were difficult to interpret in segmental terms. For these reasons, it was argued that models in which the timing of vocal tract gestures can be specified phonologically for each dialect or language (e.g. Articulatory Phonology, Browman & Goldstein Reference Browman and Goldstein1989, Reference Browman and Goldstein1992) were more adequate for dealing with such temporal variation than traditional segmental models.

Figure 3 shows a hypothetical gestural score for the word pasta ‘pasta’ in Western Andalusian. An important point in this representation is that the onset and offset of the glottal opening gesture are located before and after the tongue-tip closure corresponding to [t]. By retracting the glottal gesture with respect to the oral closure, a gestural score of the same word in Argentinean or Puerto Rican Spanish (which both tended to exhibit more preaspiration and less postaspiration than WAS) could be obtained without positing a segmental contrast (e.g. [hth] vs. [ht]). Such an analysis is in line with proposals that languages can differ significantly in the articulatory timing of similar segmental sequences (Browman & Goldstein Reference Browman, Goldstein, Kingston and Beckman1990, Byrd Reference Byrd1996, Zsiga Reference Zsiga2000, among others).

Figure 3

Hypothetical gestural score of the word pasta ‘pasta’ in Western Andalusian Spanish.

Following work on the gestural basis of syllable structure (Browman & Goldstein Reference Browman, Goldstein, Bell-Berti and Raphael1995, Goldstein, Byrd & Saltzman Reference Goldstein, Byrd, Saltzman and Arbib2006), Torreira (Reference Torreira2007b) further hypothesized that the occurrence of postaspiration in WAS [hp + voiceless stop] clusters may have arisen diachronically due to a discrete shift in phasing between glottal and oral gestures, from an unstable phasing relationship across a syllable boundary (e.g. [Vh.CV]), to a more stable in-phase coordination in syllable onset position (i.e. [V.ChV]). Although this hypothesis was advanced in order to explain a diachronic change, Parrell (Reference Parrell2012) has addressed this issue in a laboratory experiment by manipulating speech rate in WAS utterances containing an [ht] cluster, and claims to have found evidence of a switch from productions with short to long VOT as rate increased. Moreover, it is also claimed in this study that the variability observed in the elicited productions of [ht] clusters displays hallmarks of phase transitions in human coordination.

The studies reviewed above propose that the realization of [h + voiceless stop] clusters in WAS results simply from a dialect-specific realignment between glottal and supraglottal gestures leading to extensive articulatory overlap. However, this interpretation seems to neglect the fact that in WAS, [h + voiceless stop] clusters consistently display longer stop closures than intervocalic stops and stops preceded by [l]. An explanation entirely based on the notion of articulatory overlap predicts that the involved gestures will be coproduced within a narrower time window, but it does not predict increases in the duration of any of the gestures. This is even more evident in cases in which the lengthened second consonant in the [hC] cluster does not share its main articulator with [h], let alone with the historical /s/. For instance, it is difficult to imagine how a delayed [h] glottal gesture in an [hp] cluster or a reduced and overlapped tongue-tip gesture in an [sp] cluster might lead to an online lengthening of the upcoming [p] closure produced at the lips.

For this reason, it could be argued that a segmental analysis of WAS [h + voiceless stop] clusters is still plausible: WAS may have developed a series of voiceless stop segments characterized by long oral closures and variable aspiration, i.e. [pːh], [tːh], [kːh]. Under this hypothesis, preaspiration could be either an additional cue of these long aspirated stops, i.e. [hpːh], [htːh], [hkːh], as in the fortis stops of several Nordic dialects (Helgason Reference Helgason2002, Helgason & Ringen Reference Helgason and Ringen2008) and voiceless geminate stops in several Italian varieties (Stevens & Hajek Reference Stevens and Hajek2010), or could simply be the manifestation of the [h] segment in the consonant cluster, i.e. [hpːh], [htːh], [hkːh]. O'Neill (Reference O'Neill2009) examined the durational patterns arising from phonological sequences consisting of a vowel, an underlying /s/, and voiceless stop consonant in WAS. It was found in this study that the duration of the complete segmental sequence was longer in cases exhibiting preaspiration than in cases displaying no preaspiration and long VOT. This was interpreted as evidence that WAS speakers sometimes collapse [h + voiceless stop] clusters into one single segment, an aspirated stop. This conclusion, however, must be taken with caution, since average differences between two groups of transcribed acoustic realizations do not necessarily arise, as is claimed in this study, from two distinct phonological categories. Moreover, this same study also found a trade-off between preaspiration and VOT duration on the one hand, and closure duration on the other, suggesting that variation in pre- and postaspiration is caused by changes in the timing of glottal and supraglottal gestures.

1.4 Manipulating speech rate and stress placement

One way of investigating if aspirated stops in WAS result from a coarticulatory process or from a segmental rule is to examine their behavior under changes of speech rate and stress placement. There are three reasons why manipulating these two variables can help us answer this question.

First, speech rate and stress can be expected to affect the degrees of coarticulation and articulatory overlap between segments. A substantial body of research has shown that segments produced at faster rates and unstressed syllables are more sensitive to coarticulatory effects than segments spoken at slow speech rates and in stressed syllables (Lindblom Reference Lindblom1963, Gay Reference Gay1981, Browman & Goldstein Reference Browman, Goldstein, Kingston and Beckman1990, Fourakis Reference Fourakis1991, Moon & Lindblom Reference Moon and Lindblom1994, Byrd & Tan Reference Byrd and Tan1996, Davidson Reference Davidson2006, among many others). If postaspiration in Andalusian [h + voiceless stop] clusters is caused by changes in intergestural timing, its duration can be expected to be longer at faster speech rates and in unstressed stop consonants. Parrell (Reference Parrell2012) provides evidence for longer periods of postaspiration at faster speech rates, but the materials used in this study only included consonant [t], and only one carrier word. The present study intends to replicate these findings for [p] an [k], and for extended lexical materials.

Second, Kessinger & Blumstein (Reference Kessinger and Blumstein1997) found that postaspiration duration (measured as Voice Onset Time) is sensitive to stress and speech rate in languages in which it is an important characteristic of voiceless stop segments. VOT in voiceless stops was longer at slow speech rates and in stressed syllables in English and Thai, but not in French. Although postaspiration in Western Andalusian Spanish is likely to play a different role than in these languages, it may still be expected to be enhanced in prosodically prominent consonants and to covary with speech rate if it is intended by speakers as part of the stop segment.

Third, if variability in the amounts of preaspiration and postaspiration around stop closures is caused by variable degrees of articulatory overlap, trade-offs between preaspiration and closure duration on the one hand, and postaspiration duration on the other, should be observed. By manipulating speech rate and stress, we hope to introduce the amounts of temporal variability necessary for these trade-offs to emerge. Parrell (Reference Parrell2012) found evidence of a temporal tradeoff between VOT and preaspiration durations in WAS [ht] clusters spoken at different speech rates. In this study we further manipulate stress location, and also examine [hk] and [hp] clusters.

Thus, we expect that changes in speech rate and in the location of stress should help us investigate the nature of aspirated stops in WAS. The following section presents a production experiment in which these two variables were manipulated.