Conclusion - AN INTRODUCTION TO PHONOLOGICAL VARIATION, FRENCH SCHWA,

CHAPTER I. AN INTRODUCTION TO PHONOLOGICAL VARIATION, FRENCH SCHWA,

I.6 Conclusion

The aim of the present work is to provide empirical evidence bearing on a research question which has received little attention in the psycholinguistic literature: the production of phonological variants. In order to do so, we will examine the production of French schwa words’ variants (i.e., the schwa and the non-schwa variants). We will investigate the nature of the alternation process and its locus. We will do so within the framework of abstractionist psycholinguistic models of speech production, which provide the most detailed insight into the architecture of the language production system to date. In these models, three different accounts of schwa alternation may be considered, depending on the processing stage involved. The alternation may arise either during phonetic encoding (hereafter phonetic account), during phonological encoding (i.e., phonological account), or during lexeme retrieval (i.e., lexical account). We will ask the question of whether schwa alternation is better accounted for by a phonetic, phonological or lexical account⁸. These three alternative accounts are illustrated in Figure 5 to Figure 7 within the framework of Levelt et al.‘s model.

8 The conception of French schwa alternation as an epenthetic vocoide inserted for articulatory reasons will not be considered in this work. In our view, this conception of schwa would only be relevant if the clusters in which schwa was inserted did not exist in the same positions in non-schwa words. Epenthetic vocoide are inserted in some clusters, but these insertions have nothing to do with the alternation between a full schwa and zero.

Figure 5. Phonetic account of French schwa alternation. The parameter for the syllable [

Phonetic account of French schwa alternation. The duration for the syllable [&] is set to a minimum, leading to the disappearance

of the schwa in the output.

51 duration

appearance

Figure 6. Phonological accounts of schwa alte deleted through a deletion rul

deletion rule (middle

Phonological accounts of schwa alternation. Schwa is complete a deletion rule (left panel), schwa is partially deleted through deletion rule (middle panel) and schwa is inserted through an insertion rule

(right panel).

completely partially deleted through a

an insertion rule

Figure 7. Lexical

According to the phonetic accoun

schwa. The outputs of the phonological and phonetic encoding still contain th

Schwa becomes inaudible when the phonetic parameters for loudness and duration are set to a minimum. This phonetic account is in line with Articulatory Ph

that schwa is “hidden” by the surrounding consonants’ gestures.

Secondly, according to the phonological account, one variant only is stored in the lexicon.

Schwa is either deleted or inserted during the phonological encoding of the

upon the theory. The deletion can either be complete (everything is deleted) or incomplete.

Finally, according to the lexical account, the two variants of schwa words are represented in the lexicon, the more activated variant being chosen

abstractionist models of word production,

Lexical account of schwa alternation. The two variants are represented in the lexicon.

According to the phonetic account, the mental representation of schwa wor of the phonological and phonetic encoding still contain th

when the phonetic parameters for loudness and duration are set to a minimum. This phonetic account is in line with Articulatory Phonology, which assumes that schwa is “hidden” by the surrounding consonants’ gestures.

ccording to the phonological account, one variant only is stored in the lexicon.

Schwa is either deleted or inserted during the phonological encoding of the

upon the theory. The deletion can either be complete (everything is deleted) or incomplete.

ccording to the lexical account, the two variants of schwa words are represented in the lexicon, the more activated variant being chosen for production. Within

abstractionist models of word production, each variant is represented by one abstract

53 two variants are

schwa words contains the of the phonological and phonetic encoding still contain the schwa.

when the phonetic parameters for loudness and duration are set to onology, which assumes

ccording to the phonological account, one variant only is stored in the lexicon.

Schwa is either deleted or inserted during the phonological encoding of the word, depending upon the theory. The deletion can either be complete (everything is deleted) or incomplete.

ccording to the lexical account, the two variants of schwa words are represented in Within the framework of each variant is represented by one abstract

representation (i.e., abstract variants model). In an exemplarist conception of the lexicon, each variant would, by contrast, be represented with several tokens of each variant.

In addition to the representations and processes underlying the production of schwa words, this work will address several additional issues. We will examine the exact nature of lexical representations (i.e., abstract versus fully phonetically detailed), the role of contextual variables in the production of a given schwa word’s variants, the conditions leading to the construction of lexical representations for novel schwa words, and the recognition of novel schwa words.

Unlike previous studies examining schwa alternation in French, our work is not inserted in an a priori phonological framework but is above all empirical. In order to gather the necessary data, we will use methodological research tools from both phonetics and psycholinguistics. In the first empirical chapter, we will present two phonetic off-line studies. The first phonetic study presents a detailed acoustic analysis of clusters in non-schwa variants and identical underlying clusters. The second phonetic study is based on a large corpus of French radio-broadcasted speech. These two studies will contribute off-line evidence about the nature of the alternation process.

In the following empirical chapters (Chapter III to VI), we will present ten on-line experiments. These studies will contribute to our understanding of the exact nature of the representation of schwa words and of the underlying mechanisms (and their time courses) leading to the production of schwa versus non-schwa variants.

This pluridisciplinary approach should allow us to start investigating a new research area in psycholinguistic research, the production of non-canonical speech and connected speech processes. In addition, we will be able to provide new insights into French schwa, an already well-studied phenomenon but around which many questions remain open.

PHONETIC ANALYSES

II.1 Introduction

The aim of this chapter is to investigate the output of the production process involving schwa words so as to provide empirical data on the nature (phonetic versus phonological or lexical) of the alternation process. As seen in Chapter I, in most phonological theories, schwa alternation is considered a categorical, phonological process. Surprisingly however, to our knowledge, no empirical study has yet provided satisfactory data supporting this account.

On the other hand, this predominant conception of French schwa alternation has not remained completely unchallenged. At least two studies have provided empirical evidence suggesting that schwa alternation could be better accounted for by a gradient phonetic process of reduction. Barnes and Kavitskaya (2002) conducted an articulatory study (i.e., lip rounding measures) on partially homophonic sequences. They observed maximal lip rounding for tokens realized with the schwa (e.g., que Lannes ‘that Lannes’), medium rounding for non-schwa variants’ clusters (qu’la femelle ‘that the female’) and minimum rounding for non-schwa tokens (e.g., clavecin ‘harpsichord’, where schwa is assumed to be absent from the underlying representation). On the basis of these results, the authors conclude that the alternation process is gradient and better explained by a gradual overlap of gestures, in line with the basic principles of Articulatory Phonology (Browman & Goldstein, 1992). Smorodinsksy (1998) reaches a similar conclusion. She compared the position of the tongue during the production of consonant clusters in different conditions, including in non-schwa variants’ clusters (e.g., et t’nir ‘and hold’) and in identical underlying clusters (e.g., ethnie ‘ethnic group’). She finds a significant difference in the vertical displacements of the tongue between these two conditions, suggesting that a schwa target is still present in the non-schwa variants’ clusters. According to Smorodinsky, this finding suggests that the schwa is not deleted but rather hidden by the surrounding consonants’ gestures.

In this chapter, we present two phonetic studies whose aim is to provide further empirical data about the nature of the alternation process. Two opposite views will be contrasted;

schwa alternation as the result of a gradient process of phonetic reduction (i.e., phonetic account) versus schwa alternation as a categorical process arising at an earlier stage of the production process (i.e., phonological or lexical accounts).

Phonetic study 1 is concerned with the acoustic specificities of consonant clusters in non-schwa variants compared to identical underlying clusters and identical clusters in pseudowords. We investigate whether clusters in non-schwa variants show evidence in favor of an underlying vowel that would be incompletely deleted or hidden by gestural overlap.

In Phonetic study 2, we investigate the nature of the variables conditioning the alternation between schwa and non-schwa variants in a large corpus of radio-broadcasted speech and their similarities/differences to/from the variables influencing the duration of schwa in the same corpus. Following Raymond, Dautricourt and Hume (2006), we assume that information on the nature of the variables conditioning the presence versus absence of schwa, and whether these variables parallel those influencing schwa duration, should inform us on the nature of the process involved in French schwa alternation.

The two studies that we present in this first empirical chapter depart from previous empirical studies on French schwa, especially in their methodology. Firstly, we take special care to check for potential confounding variables. In addition, we use large data sets, with productions taken from a large panel of speakers, in order to be able to generalize our findings. Finally, we take advantage of several methodological tools recently made available to researchers in the field. The use of an automatic alignment system allows us to study many occurrences of schwa words extracted from a large corpus of connected speech (Phonetic study 2). Furthermore, we make use of powerful statistical tools (i.e., mixed-effects models), that enable us to provide relevant statistical evidence for the data we present. Finally, in addition to manual spectrographic analyses, automatic acoustic analyses are used in order to provide objective measures of acoustical patterns (Phonetic study 1).

II.2 How similar are clusters in non-schwa variants to identical underlying clusters? (Phonetic study 1)

⁹

II.2.1 Introduction

In this first phonetic study, we investigate the schwa alternation process by means of a thorough comparison between clusters in non-schwa variants and identical underlying clusters (i.e., in schwa words). Our aim is to determine whether output forms of non-schwa variants show evidence for an underlying non-schwa vowel. This is not a trivial issue as it may inform us about the nature and locus of the alternation process.

If acoustic residues of a schwa vowel are found in output forms of non-schwa variants, they can be taken as evidence that schwa is present in the underlying representation (i.e., the lexeme contains the schwa). In that case, the locus of the alternation process would be either phonetic (i.e., schwa is present in the underlying form and reduced through a phonetic process of reduction, Smorodinsky, 1998; Barnes & Kavitskaya, 2002) or phonological, with non-schwa variants being the result of a phonological deletion rule which only partially deletes the schwa (i.e., schwa is still present at some level of representation as assumed for instance by Rialland, 1986 or Charette, 1991). Consequently, the presence of acoustic residues of the schwa vowel in non-schwa variants’ clusters would refute the proposals of a lexical locus for the alternation process (i.e., two lexemes for schwa words, one per variant) and the epenthetic account (i.e., a schwa is inserted into a non-schwa representation during phonological encoding).

In contrast, the absence of acoustic residues of the schwa vowel in non-schwa variants’

clusters would indicate that schwa is neither the endpoint of a gradient phonetic reduction nor the result of an incomplete process of deletion. Table 1 summarizes the possible accounts of the schwa alternation process according to whether acoustic residues of the schwa vowel can be found in non-schwa variants.

9 This study was realized in collaboration with Cécile Fougeron (Laboratory of Phonetic and Phonology, Paris III) who supervised the design of the experiment and the acoustic analyses. A collaboration with Christophe Veaux (IRCAM, Paris) allowed us to include automatic analyses. This study was presented at the Interspeech 2009 conference (Bürki, Fougeron, Veaux & Frauenfelder, 2009).

59 Table 1. Possible accounts of French schwa alternation according to whether acoustic residues of the schwa vowel can be found in non-schwa variants’ clusters.

Lexical

Acoustic residues of the schwa vowel could first be found in the duration of the surrounding consonants. As seen in Chapter I, Autosegmental Phonology assumes several tiers for a given word’s phonological representation. Within this framework, some authors have argued that schwa is only deleted at the segmental level. In Rialland (1986) for instance, the segmental content of schwa is deleted but its nucleus (on the syllabic tier) is nevertheless maintained. This empty temporal unit is attributed to one of the surrounding consonants, leading to a longer duration for this consonant (i.e., compensatory lengthening). Secondly, acoustic residues of an underlying schwa vowel in non-schwa variants’ consonant clusters could also surface in other acoustic features such as the presence of voicing between the two consonants of the cluster or less assimilation between the consonants.

The present study is not without precedent. Several detailed acoustic and articulatory studies have looked for residues of an underlying schwa vowel in non-schwa variants’ clusters.

These studies examined the acoustical and articulatory properties of clusters in non-schwa variants and in identical underlying clusters. Most of them compared these two cluster types in homophonic (e.g., jeu drôle ‘funny game’ versus jeu d’rôle ‘role-play’) or partially homophonic sequences (e.g., et tenir ‘and hold’ versus ethnie ‘ethnic group’). For instance, Rialland (1986) conducted an acoustic study and observed that the consonant preceding schwa in non-schwa variants is stronger and longer than coda consonants in identical underlying clusters. The consonants []and [l] found after the schwa vowel are also longer and stronger than identical underlying consonants. According to Rialland, these differences

suggest that the schwa is only partially deleted. Lebel (1968) compared the duration of the schwa’s surrounding consonants in non-schwa variants’ clusters and in underlying clusters (in words and pseudowords) in the productions of three speakers. He observed that preceding consonants are significantly longer in non-schwa variants than in underlying identical clusters.

Several articulatory studies also found differences between clusters in non-schwa variants and underlying identical clusters. For instance, Fougeron and Steriade (1999) found that in non-schwa variants’ clusters, the consonants maintain some articulatory properties of the schwa variant (e.g., amount of linguo-palatal contact, timing between gestures). As seen above, Barnes and Kavitskaya’s (2002) measures of lip rounding and Smorodinsky’s (1998) measures of tongue position also suggested differences between the two types of clusters.

These few acoustical and articulatory studies have, however, severe drawbacks (see also Côté & Morrison, 2007 for a similar discussion) which make it impossible to ascertain whether the differences found between the two cluster types can bear attribute to schwa.

Firstly, the homophonic sequences compared in these studies were not checked for various factors known to influence the consonants’ durations and other acoustical properties, such as lexical frequency (Pluymaekers, Ernestus & Baayen, 2005; Kuperman, Pluymaekers, Ernestus & Baayen, 2007), position with regard to syllabic boundaries (Browman &

Goldstein, 1995; Kochetov, 2006), word length (Crystal & House, 1990) or position of the syllable in the word (O’Shaughnessy, 1981). It is thus possible that the differences observed between clusters in non-schwa variants and identical underlying clusters in terms of duration or other acoustical/articulatory characteristics are not due to the presence of an underlying vowel but to other variables differing between the words or sequences under consideration.

For instance, Côté and Morrison (2007) provide alternative explanations to Fougeron and Steriade (1999), Smorodinsky (1998) and Barnes and Kavitskaya’s (2002) findings, involving differences in segmental context, schwa position in the word or with regard to word boundaries. A second major drawback of these studies lies in the often restricted number of participants and items. The generalization of these results may thus be questioned.

In the present study, we provide a thorough investigation of the acoustical properties of consonant clusters in non-schwa variants and underlying identical clusters produced by 33 different speakers. Special care is taken to check for the different variables known to influence these acoustical properties. We first analyze the clusters’ durations. We examine whether they are longer for non-schwa variants than for identical underlying clusters after

the variation explained by other variables known to affect segment duration is taken into account. We then investigate whether clusters in non-schwa variants show acoustic residues of an underlying vowel that is incompletely deleted or hidden by gestural overlap. In order to do so, we conduct manual and automatic comparisons between clusters in non-schwa variants and identical underlying clusters.

An additional aim of this study is to determine whether clusters in pseudowords behave like clusters in words. For the majority of schwa words, it is difficult to find a word in the French lexicon with a corresponding underlying cluster matching in terms of syllabic structure. The use of pseudowords for comparison is thus quite convenient for this reason, but one has to be sure that the gestural cohesion pattern in the cluster is not atypical because of the non-word status.

II.2.2 Method

II.2.2.1 Speakers

Thirty-three students from the Psychology Department of the University of Geneva took part in the experiment. They were all monolingual French speakers, with no reported hearing, reading or language impairment.

II.2.2.2 Corpus constitution

Material selection and preparation

We first selected 32 different CC clusters found in French schwa words (e.g., /sl/ as in cela

‘this’). For each of these clusters, we found three items: a schwa word whose non-schwa variant contains the cluster, a word with an identical underlying cluster, and a pseudoword with an identical cluster. For instance, the cluster /sl/ was associated with cela ‘this’ (i.e., schwa word), slalom (word with identical underlying cluster) and slami (pseudoword). These three items formed the three conditions that are compared in this study; the schwa cluster condition (i.e., non-schwa variant), the underlying cluster condition (i.e., non-schwa word), and the pseudoword cluster condition. Cluster position in the pseudoword was kept constant between the schwa word and the pseudoword. Furthermore, whenever possible, we chose a non-schwa word with an underlying cluster in the same position with regard to word and syllabic boundaries as in the schwa word and pseudoword. Such constraint could be satisfied for eight clusters only. For 22 clusters, we could match a word with an identical underlying

cluster but in a different position with respect to word and syllabic boundaries. For instance, for the cluster /lk/, the cluster for the schwa word was at the onset of the word (lequel ‘which one’) but the cluster for the non-schwa word was word-internal (calquait ‘copied’). For three clusters (//, /dp/, and /ds/), no words could be found containing the cluster, whatever its position.

We then inserted each of these items into a carrier sentence (e.g., J’aime les chanteurs de rap, Slami est mon préféré ‘I like rap singers, Slami is my favorite’). For the three items containing a given cluster (schwa, underlying and pseudoword), the length of the sentence as well as the position of the item in the sentence were similar. The absence of schwa in the schwa words was transcribed with an apostrophe (e.g., “c’la”), as used in many songs or comic books in French. The stimuli and sentences are reported in APPENDIX 1. We created two lists of sentences. The first list contained the items with half of the clusters and the second list the items with the other half.

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