Linguistic Typology 2019; 23(2): 263–302

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Joan Bybee and Shelece Easterday Consonant strengthening: A crosslinguistic survey and articulatory proposal https://doi.org/10.1515/lingty-2019-0015 Received April 16, 2018; accepted December 07, 2018

Abstract: Given the common intuition that consonant lenition occurs more often than fortition, we formulate this as a hypothesis, defining these sound change types in terms of decrease or increase in oral constriction. We then test the hypothesis on allophonic processes in a diverse sample of 81 languages. With the hypothesis confirmed, we examine the input and output of such sound changes in terms of manner and place of articulation and find that while decrease in oral constriction (weakening) affects most consonant types, increase in oral constriction (strengthening) is largely restricted to palatal and labial glides. We conclude that strengthening does not appear to be the simple inverse of weakening. In conclusion we suggest some possible avenues for explaining how glide strengthening may result from articulatory production pressures and speculate that strengthening and weakening can be encompassed under a single theory of sound change resulting from the automatization of production.

Keywords: phonology, consonant strengthening, lenition and fortition, allophonic variation, sound change, automatization

1 Introduction

It is generally agreed that lenition is much more common than fortition in sound changes as well as phonological processes across the languages of the world.1 This asymmetry suggests the need for special attention to fortition in order to determine if it is the simple inverse of lenition or a different phenomenon. The

Author Contribution Statement: Joan Bybee and Shelece Easterday contributed equally to the data collection, analysis, and writing of this paper 1 See Section 3 for references and discussion.

Joan Bybee [ˈdʒ͡oʊn ˈbaɪbi], Department of Linguistics, University of New Mexico, Albuquerque, NM, USA, E-mail: [email protected] Shelece Easterday [ʃəˈlis ˈistɚdeɪ], Laboratoire Dynamique du Langage, UMR 5596, CNRS - Université Lumière Lyon 2, DDL - MSH-LSE, 14 avenue Berthelot, 69363 Lyon CEDEX 07, France, E-mail: [email protected] 264 Joan Bybee and Shelece Easterday current contribution surveys consonant lenition and fortition across a database of sound changes in a systematically-constructed sample of languages. One main finding is that under the definitions examined here, fortition is not the simple mirror-image of lenition, but rather is much more restricted in its occurrence. The most common type of consonant fortition of the processes surveyed is the strengthening of palatal and labial glides to fricatives, affricates, or stops. The presentation is organized as follows: first in the following section, we explain our theoretical perspective and the reason for choosing sound change as the basis of the study. In Section 3 we review briefly the copious literature on consonant lenition and fortition (also often called weakening and strengthening, terms we will use without implying a difference from lenition and fortition) and propose an operational definition of these sound changes based on articulatory properties. When rates and characteristics of weakening and strengthening processes are compared in a diverse cross-linguistic sample in Section 4, we find that fortition is not the simple mirror-image of lenition, but is much more restricted in its properties. In Section 5, we bring up factors that may contribute to the predominance of palatal and labial glide strengthening. We examine the automatization of production in light of recent studies on the effect of practice on motor movement and suggest that movement optimization may lead to ‘overshoot’ resulting in apparent strengthening, especially for glide articulations made with bulky articulators.

2 Diachronic typology and complex adaptive systems theory applied to phonology

We frame our study as a contribution to diachronic typology, as explicated and practiced by Joseph H. Greenberg (1969). Greenberg’s observation was that crosslinguistic patterns arise because languages change in very similar ways: “[s]ynchronic regularities are merely the consequence of [diachronic] forces. It is not so much … that ‘exceptions’ are explained historically, but that the true regularity is contained in the dynamic principles themselves” (1969: 186). That the more powerful language universals are contained in pathways of change has been abundantly illustrated in the explication of grammaticalization pathways, because synchronic states may reflect any position upon such a path of change, making the individual languages quite different from one another, while the path itself is repeated in similar ways across time and space (Bybee et al. 1994; Greenberg 1978; Heine & Kuteva 2002). Phonological pathways have also been established, especially for lenition processes, as we will see in Section 3 Consonant strengthening 265

(Hock 1986; Hooper 1976; Lass & Anderson 1975; Lavoie 2001). The dynamic process of sound change has also been shown to create synchronic phenomena such as distinctive features (Mielke 2008), phoneme inventories (Bybee & Beckner 2015), phonotactic patterns (Blevins 2004; Bybee 2001; Easterday 2017) and phonological alternations (Blevins 2004 and many others). Diachronic typology is a model with the same properties as complex adaptive or self-organizing systems (Bybee 2006; Lindblom et al. 1984; Lorenz 1993). In this view of language all aspects of structure are emergent rather than given a priori. Like other complex adaptive systems, such as physical or biological systems, language evolution works with initial states in which certain sub- stances with inherent properties are given (in the case of language, phonetic substance and conceptual or semantic substance); the substance is molded by natural processes (which in the phonetic domain are derived from the properties of the articulatory and perceptual systems) recurring in dynamic events (in the case of language, usage events). Repetition over multiple events leads to the emergence of apparent structure. Our application of diachronic typology or emergent phonology proceeds as follows (based on Bybee 2001, Bybee 2006). First, one observes generalizations in crosslinguistic patterns in the languages of the world, such as Greenberg’s observation (based on Ferguson 1966) that the presence of phonemic nasal vowels in a language implies the presence of oral vowels (Greenberg 1969). Second, one considers how such a generalization arises through diachronic change. In the example given, the proposal is that nasal vowels arise from oral vowels through assimilation to a nasal consonant with the subsequent deletion of the nasal consonant leaving the nasal vowels intact to contrast with oral vowels. Third, one seeks an explanation for the diachronic change that creates the crosslinguistic generalization. In the case of phonology, the diachronic changes that need to be explained are primarily sound changes. In the particular case used as an example here, the explanation would address why vowels tend to become nasalized preceding a nasal consonant and further why that nasal consonant sometimes weakens. The assumption made in this theory is that certain trajectories of phonological change are common across languages: that is, sound changes are similar across languages and the effect of sound change on phonemic structure, (mor- pho)phonological alternations and phonotactics is similar across languages. This theoretical structure assumes that diachronic changes provide genuine explanations for crosslinguistic generalizations about phonological processes and alternations, phoneme inventories, distinctive features and phonotactic patterns. Note that in this theoretical perspective there are no constraints either violable or not; there are only active forces, whose properties we need to study 266 Joan Bybee and Shelece Easterday further, molding substance in such a way as to create apparent structure. That means both common and rare outcomes may be created by the same processes. In the current paper, we focus on phonetically conditioned sound change to help us identify the phonetic forces that cause change and create certain aspects of phonological systems. Almost all researchers today agree that sound change has phonetic motivation, though the exact nature of the phonetic forces and whether they are articulatory or perceptual is regularly debated. The current paper examines the beginning stages of sound change, as represented by allophonic variation. As argued in Bybee (2012), many (if not most) sound changes begin as a result of the automatization of production and thus require an articulatory explanation. There are of course theories of sound change that emphasize the acoustic/perceptual contribution (Guion 1998; Ohala 1981, Ohala 2003; inter alia), but many of these theories rely upon an initial change based in coarticulation, which is then subsequently affected by perception.2 Moreover, the theory of misperception by hypocorrection as espoused by Ohala is difficult to apply to lenition processes, since the basic mechanism in the theory is the attribution by listeners of a phonetic cue to a segment rather than to properties of the context. For the most common type of lenition, the change of a stop to a fricative intervocalically (see Section 4.2) this would mean misattributing the continuancy of the surrounding vowels to the stop consonant(s), which seems highly implausible. Indeed, Ohala (2003) implies that this theory is not applicable to sound changes other than assimilations.3 In Sections 3 and 5, we will say more about our theoretical proposal regarding the nature of sound change. Also, in accord with the general outline above of language as a complex adaptive system, we accept the proposal that sound change occurs during language use. Our hypothesis is that speech, as a highly practiced neuromotor activity, is subject to subtle changes in motor routines that make them more efficient (Kapatsinski 2018; Lindblom 1990). These include the coarticulatory effects of anticipating upcoming articulatory gestures, continuing gestures past the segment they are associated with, and reducing the magnitude and/or duration of gestures. Strong evidence for the role of usage in sound change comes from studies of lexical diffusion. It is frequently observed that sound change and phonetic variation affect words and phrases of high token frequency before those of lower frequency (Bybee 2000, Bybee 2001, Bybee 2012; Hay & Foulkes 2016;

2 A notable exception is Licensing by Cue (Steriade 1997), in which phonemic neutralizations are claimed to be motivated by the acoustic properties of the environment. 3 Ohala (2003: 677): “The preceding account of sound change, I believe, applies to the vast majority of common sound changes considered to be assimilative…” Consonant strengthening 267 and others).4 This phenomenon supports the hypothesis that variation and change in sounds is due to the automatization of production, since the more highly-practiced items undergo change earlier and to a greater extent than other items. To summarize this section, as others have argued, the processes of diachronic change hold the key to explanations for why sound systems are as they are. The dynamic forces that cause mutations in the sounds of language provide the explanatory material for understanding phonological alternations and distributions. These processes start with sound change and then go on to involve cognitive generalization of syllable structure patterns or phonotactics, as well as lexical and morphological connections among sounds.

3 Consonant lenition and fortition

3.1 Background

Traditionally, the major classes of sound change include two phenomena defined by changes in the relative strength of a sound: lenition and fortition. In the most general terms, lenition is the weakening of a consonant and fortition is the strengthening of a consonant. It is widely stated that of these two types of sound change, lenition is more frequent. For example, Mowrey and Pagliuca state that “instances of consonantal decay greatly outnumber those of consonantal strengthening” (1995: 97; see also Cser 2003: 18). Indeed, fortition is often not given as much consideration as lenition: see the minor role accorded it in Brandão de Carvalho et al. (2008), which aims to be a thorough reference on these phenomena. Honeybone (2008) and Blevins (2015) also assume lenition is more common, but the statements below indicate that there is disagreement as to whether the typical characterization of lenition and fortition, which puts them in direct opposition with one another, is an accurate one.

This focus on ‘lenition’ and ‘weakening’ will also mean that I largely ignore their uncom- moner cousins ‘fortition’ and ‘strengthening’.[… C]ases of real fortition are vanishingly rare, and it is by no means obvious that they really are the literal ‘opposite’ of lenition. (Honeybone 2008: 10)

4 A few changes have been observed to affect low frequency words first (Bybee 2012; Hay et al. 2015). These studies also support the idea that sound change is highly affected by and takes place during usage-events. 268 Joan Bybee and Shelece Easterday

While regular sound changes involving strengthening are, overall, less common than weakening, and tend to be associated with strong prosodic positions, they need not be, and require a place in any sound change typology. […] In addition to glide-strengthening […], strengthenings that are near mirror-images of common weakening processes are also attested. (Blevins 2015: 490)

The many views of the prevalence of lenition seem to center around an intuition that lenition results in ease of articulation, or as Kirchner puts it, that lenition is “driven by a phonetic imperative to minimize articulatory effort” (1998: 2–3). Indeed, there is a traditional view of sound change as resulting from sloppy or lazy articulations (Hockett 1942; Hock 1986). The characterization of lenited articulations as sloppy, however, does not explain the consistency across speakers of the same variety in the way they attain efficiency. In fact, the high level of phonetic similarity across speakers of the same dialect follows from the fact that speech is a highly practiced and finely tuned neuromotor activity. As with other highly-skilled motor patterns, efficiency is achieved through automatization which leads to reduction and overlap of sequences of gestures (Bybee 2001, Bybee 2012; Kapatsinski 2018; Lindblom 1990; Pouplier 2012). Our view is that the automatization process leads to systematic sound change, arising from coarticulation and reduction occurring in casual speech (Browman & Goldstein 1991, Browman & Goldstein 1992; Mowrey & Pagliuca 1995), which often appears to be reductive, but is not sloppy or idiosyncratic. As this view privileges lenition and assimilation, it becomes all the more important to study fortition. The goals of the present work are to offer some clarification of these issues by examining lenition and fortition processes in a diverse typological sample. Specifically, we seek to (i) quantify the relative crosslinguistic frequency of a select set of lenition and fortition processes; and (ii) determine whether the distributions and characteristics of these processes support the idea that they are mirror-images of one another. A further goal, in response to a general under- representation of fortition in the literature on consonant strength, is to (iii) pay particular attention to describing and characterizing the fortition processes in our study. For now, however, we turn to a discussion of the definitional pro- blems which make it difficult to address these questions. Sound change processes typically characterized as lenition or weakening often include consonant voicing, degemination, flapping, spirantization, approximantization, debuccalization, and elision, but may also include deas- piration, de-ejectivization, and even place assimilation, among others. Although these processes are taken as intuitive examples of consonant weakening, they form a heterogeneous group which has proven difficult to define in a collective way. In addition, as Recasens (2002) demonstrates, the sound changes on this Consonant strengthening 269 list may arise from different types of phonetic mechanisms. Similarly, processes of fortition are heterogeneous if processes such as fricatives becoming affricates and glides becoming fricatives are included along with the gemination of consonants and the aspiration of stops. Honeybone (2008) provides an analysis of the long history of interest in consonant weakening or lenition in sound change and in phonology. As noted above, a recurring problem is that there seem to be different types of consonant weakening, leading to a variety of definitions. Recent literature has largely settled on two types of consonant weakening, or two overlapping factors, called ‘sonorization’ and ‘opening’ by Lass and Anderson (1975) and variously characterized by other authors (for example, Lavoie 2001; Szigetvári 2008). Here the two types will be illustrated in terms of two different pathways of change (1)–(2):

(1) Sonorization increases the vowel-like properties of a consonant, including both voicing and a decrease in the degree of constriction in the oral cavity, as in the sequence: p > b > w. Descriptions of this type of weakening often refer to the sonority hierarchy also used to describe sequences of segments within the syllable.

(2) Reduction toward deletion maintains the laryngeal state of the consonant, but weakens the oral articulation leading to debuccalization and eventual deletion, as in the sequence: p > f > h > Ø.

It is important to note that these characterizations are descriptive. Any attempt to move directly from these statements to explanation leads to circularity: how do we know any particular step on the path is a lenition? To answer that it is lenition if the outcome is more sonorous or closer to deletion is to refer back to the proposed path. Definitions of sonority in terms of the distribution of consonants in syllable onsets or codas are additionally problematic because many sections of the sonority scale in relation to syllable structure are controversial (see the discussion in Szigetvári 2008). Another approach identifies weakening or strengthening according to the environments in which the change occurs. For example, Buizza and Plug (2012) argue that voiceless stop affrication in British Received Pronunciation (as in radio broadcasts) is a strengthening because it occurs in a strong context: word- initial position. Lavoie (2001: 45) takes a similar position on affrication in English and in her crosslinguistic analysis. Honeybone (2001) also argues that affrication and frication in Liverpool English are leniting processes, given the contexts in which they occur. Again there is a concern for circularity because the ‘strong’ and ‘weak’ positions have been established on the basis of what sound 270 Joan Bybee and Shelece Easterday changes they tend to support. Moreover, there are clear cases of weakening in designated ‘strong’ positions such as word-initial position. For example, in some dialects of Spanish /s/ undergoes debuccalization in syllable-initial position including word-initially (Raymond & Brown 2012). Similarly, word-initial /f/ in Spanish variably debuccalized to /h/ and eventually Ø, starting in medieval Spanish (Brown & Raymond 2012). If fortition is the mirror-image of lenition, we would expect to find sound changes or allophonic processes that simply run lenition processes in the opposite direction: glides become voiced fricatives or stops, voiced obstruents become voiceless, the glottal fricative [h] becomes an oral fricative buccalizing to [f], [s] or [x], the glottal stop follows suit, yielding [p], [t] or [k], and so on, with all these occurring in ‘strong’ environments. As far as we know, no one has claimed that consonant strengthening is the simple opposite of weakening. However, we know of no empirical studies that have explicitly set out to discover the range of possible strengthenings, as we intend to do here. In an attempt to ground a definition of changes in consonant strength independently of the paths of change it is supposed to explain, we turn to the articulatory characterizations of Browman and Goldstein (1991, 1992), and Mowrey and Pagliuca (1995) in which casual speech processes and the sound changes they lead to are described as the retiming of gestures and the reduction in the magnitude or duration of gestures. Retiming of gestures is often observable as assimilation though it can also result in apparent deletion or insertion of segments.Thereductioninmagnitudeorduration of a gesture is often observable as lenition, though other outcomes are possible. Regrettably we do not always have articulatory measures of magnitude or duration for the sound changes we study; nor do we have such measurements for allophonic variation in the synchronic sound systems of all the languages of the world. Nonetheless, this articulatorily-grounded definition provides us with criteria to establish that the changes of a stop to a fricative or glide are weakening processes because they involve a relative decrease in the displacement of the active articulator(s) in the stop gesture. The shortening of a coronal stop to a flap is a weakening along the duration dimension, as is degemination. Voicing of an obstruent in a voiced context (such as intervocalically) is a weakening of the glottal opening gesture, which occurs incrementally as shown in Browman and Goldstein (1992). Lavoie (2001) shows that such weakened obstruents also have a shortened oral gesture. Gordon notes inconsistencies in the “mapping between articulatory effort and (acoustic) intensity” (2016: 152) in many of the attempts to define consonant strength: sometimes a more open articulation may result in greater intensity. For example, the categorization of the affrication of a voiceless stop as lenition or Consonant strengthening 271 fortition is controversial, as the outcome — the affricate — has a heightened acoustic presence, suggesting to some a strengthening (Foley 1977). However, others see the decay in the stop closure as a weakening (Lass 1984; Lass & Anderson 1975; Pagliuca & Mowrey 1987). Adopting a purely articulatory definition of consonant strength provides a consistent criterion for categorizing processes as strengthening or weakening. As Lavoie (2001) points out, the advantage of the articulatory definition with its dual parameters of reduction in magnitude and duration and its application to oral as well as laryngeal gestures allows the same consonant to follow different paths of change. That is, both the sonorization pathway in (1) and the debuccalization or reduction to zero pathways in (2) are covered by the articulatory definition. Similarly, Kirchner notes that defining the core property of lenition as “somereductioninconstrictiondegreeorduration” unites a number of processes that are uncontroversially considered to be lenition, including degemination, flapping, spirantization, and debuccalization (2004: 313). For the investigation reported here, then, we have adopted a definition of lenition that is tied to a measurable physical phenomenon: gesture reduction. However, as the term “gesture” has a technical definition in Articulatory Phonology, here we specifically define lenition as a reduction in the magnitude and/or duration of an articulatory movement. An additional important point is that a concrete theory underlies this choice: as mentioned above, sound change can be viewed as the automatization of production. Because highly practiced behavior becomes more efficient over multiple events, the theory of the automatization of production explains why lenition and assimilation are so common among sound changes and phonological processes.

3.2 An articulatory definition of consonant strength changes

Following the reasoning above, if we take a reduction in the magnitude or duration of an articulatory movement to be a weakening, then its inverse, an increase in the magnitude or duration of an articulatory movement, can be considered a strengthening. For the present study, we choose to set aside the parameter of duration as found in flapping, gemination and degemination, and instead focus entirely on changes in the magnitude of articulatory movements, which we acknowledge may be accompanied by changes in duration. Here we operationalize a change in the magnitude of an articulatory movement as a change in the manner of articulation, which reflects the relative degree of vocal tract 272 Joan Bybee and Shelece Easterday constriction involved in producing a consonant. We further restrict our study to changes in the degree of oral constriction of a consonant. Finally, due to the difficulty in determining the precise order of their degrees of constriction relative to one another and to other manners of articulation, we exclude from the present analysis the following sounds which are typically grouped together under the term ‘liquids’: lateral approximants, flaps/taps, and trills. This brings us to the following scale of consonant strength to be used in this study (3):

(3) Consonant strength scale: central approximant > fricative > affricate > stop5

We define a weakening as any change whose input is to the right of its output on this scale, and a strengthening as any change whose input is to the left of its output. Any such decrease or increase in the degree of oral constriction is of interest to our investigation. For example, a process by which a velar stop is reported to become a velar fricative in some context is considered a weakening, because the outcome has undergone a relative decrease in the constriction degree: a fricative has a lesser degree of oral constriction than a stop. The position of affricates on this scale deserves some further comment. As mentioned above, a few researchers view a change from stop to affricate as a strengthening due to the increase in acoustic energy (Foley 1977). However, the majority consensus seems to be that from an articulatory point of view, affrication of a stop results from the partial decay of the stop closure and thus constitutes a weakening (Honeybone 2001; Lass 1984; Lass & Anderson 1975; Pagliuca & Mowrey 1987). In the variation data Honeybone presents from the Liverpool dialect of English, the affrication appears along with fricative var- iants, suggesting a process by which stop weakening moves from stop to affricate to fricative (cf. the Second Germanic Consonant Shift). The fact that there is not complete agreement on the categorization of affrication (Buizza & Plug 2012) may suggest that there is more than one type of stop affrication, an interesting issue that we will not attempt to resolve here (but see Section 4.4). In terms of our working definition which by necessity applies to synchronic states, the position of affricates on the scale is justified by their intermediate position between fricatives and stops: as fricatives have a more open articulation than stops, an obstruent that has both closure and frication must be judged as more open than a stop, which has a complete closure.

5 Both oral and nasal stops are included in this category. Consonant strengthening 273

Additionally, we consider the two following process types because they also affect the degree of oral constriction of a consonant (4)–(5):

(4) Debuccalization: a process by which a consonant loses its oral constriction but retains a glottal articulation.

(5) Buccalization: a process by which a glottal consonant gains an oral constriction.

We exclude from the present analysis all cases of total assimilation and consonant deletion. We also do not include processes like the apparent insertion of a stop from a cluster of a nasal and a liquid, as in Old English bræmle > Present Day English bramble. Such changes are better analyzed as retiming, as the surrounding consonants supply the gestures for the emergent stop (Browman & Goldstein 1991; Pagliuca & Mowrey 1987). On similar grounds we limit the current analysis to processes which are conditioned by vocalic, stress, or domain-related environments, excluding any process which is supported by a consonantal articulation in the immediate context. Although we acknowledge that the set of weakenings and strengthenings examined here is more restricted than typical definitions of lenition and fortition, our working definition allowsustocompareoppositeprocessesin a systematic way and thus address common assumptions about these types of sound change. It is this approach, in addition to our sampling methodology (see below), that sets our study apart from previous typological studies of consonant weakening and strengthening (Cser 2003; Kirchner 1998; Lavoie 2001). In those previous studies, lenition and fortition are first defined in the traditional manner in terms of heterogeneous process types, and unifying articulatory or phonetic interpretations of consonant strength are proposed after the fact.

4 Survey of lenition and fortition in AlloPhon

Crosslinguistic diversity arises because the same mechanisms interact in different ways over time depending upon a number of factors, including what conventional aspects of a language are already established, such as the use of stress or tone, rhythm type, phonotactics, morphosyntax, and possibly other factors such as distribution patterns across lexical items: for example, it has been found that languages with different degrees of syllable structure complexity tend to have 274 Joan Bybee and Shelece Easterday different kinds of vowel reduction patterns (Easterday 2017). Only by casting a wide net and studying a representative sample of the world’s languages can we appreci- ate the range of questions concerning these factors and the way they interact. Moreover, a firm grounding in empirical data allows us to test hypotheses concerning lenition and fortition that are implicit and explicit in much of the phonological literature. Therefore we address the research questions of this paper in AlloPhon, a database of allophonic variation in a sample of 81 diverse languages which were chosen independently of the phenomenon under study.

4.1 Principles behind construction of AlloPhon

The primary challenge for compiling a crosslinguistic database of sound changes is that documented sound changes are biased towards a small set of languages for which there is a long written tradition. Most sound changes have taken place in the past in languages that were not written and thus leave only faint traces, or traces that are interpretable only through reconstruction. However, the use of reconstructed changes risks circularity, as the reconstruction of the phonetic content of proto-phonemes relies in part upon the researcher’s intuitions about what is a plausible sound change. Because of the limitations on diachronic data, recent crosslinguistic studies of lenition (and fortition) have used convenience samples of languages with some written history or reconstruction (Cser 2003), or synchronic descriptions selected for convenience (Kirchner 1998; Lavoie 2001). Such studies are necessarily biased towards well-studied languages, particularly those of Europe and its sur- rounds, and cannot yield an accurate picture of the distribution of lenition and fortition across language families and geographic regions of the globe. In the hope of eliminating bias from reconstruction and from the selection of languages for convenience, we have elected to use synchronic data from a systematically diversified sample of languages, described below. While there are differences of opinion about the point at which a gradual change becomes a sound change, our underlying assumption is that any allophonic variation is the result of an ongoing or previous phonetic process and a potential source of further change. Choosing to restrict our data to phonetically-conditioned alternations (allophonic variation), we are likely to record processes that have not yet been disrupted by morphologization, inver- sion or telescoping. This very shallow time depth should provide us with information about the beginnings of sound changes, as well as the small increments that make up longer trajectories of change. The data, then, provide both synchronic and diachronic evidence. Consonant strengthening 275

4.1.1 The AlloPhon language sample

Among the known biases in crosslinguistic work, genealogical bias is the most prominent. One can select languages so as to avoid as much genealogical bias as possible, or one may test for it in post-hoc analyses of the results of a survey (Bickel 2008; Dryer 2000; Janssen et al. 2006; Maslova 2000; Perkins 1992; Rijkhoff & Bakker 1998). Our database, hereafter referred to as AlloPhon, builds in genealogical control from the beginning. It is a stratified probability sample in which the languages are chosen randomly within a predetermined number of genealogical categories representing historically diverse branches or stocks at a particular time depth. Because of the random nature of the language selection and the fact that genealogical bias is controlled for, this kind of sample is appropriate for our goal of investigating the range and variation of allophonic processes that occur in the world’s languages. The sample for AlloPhon, which contains 81 languages, is based heavily on the sample used in Bybee et al. (1994) which was constructed using a sampling procedure that controls for genealogical relations as proposed in Perkins (1992). A table listing the 81 languages can be found in the online Appendix. The AlloPhon sample contains some languages that are known to be related to one another. However, the approximate time depth of these relations is over 2000 years: for instance, the Indo-European languages included in the sample are Continental Scandinavian (Germanic), Modern Greek (Greek), Latin (Romance), Palula (Indo-Aryan) and Baluchi (Iranian). Perkins (1989) demonstrates that phonological change (at least in phoneme inventories) operates at a rate that makes the phonology of a language separated from its sisters for 2000 years relatively independent. It is important to stress that the AlloPhon language sample was constructed to examine sound change in general, and that the only criterion for inclusion, after genealogical stratification, was the availability of adequate descriptions of allophonic processes. Thus the language sample was constructed independently of our specific research questions regarding consonant strength changes. This approach allows us to establish relative crosslinguistic frequencies of weakening and strengthening, and is one of the important ways in which the current work differs from previous typological studies of the topic. The samples in Cser (2003), Kirchner (1998), and Lavoie (1996, 2001) – besides having many closely related languages and including reconstructed and historical morphophonological changes in addition to synchronic patterns – are composed entirely of languages which were known to have the lenition and/or fortition processes sought by the authors of those studies. 276 Joan Bybee and Shelece Easterday

4.1.2 Data collection and coding

The data for AlloPhon was gathered from published sources, including reference grammars, phonological descriptions, and dictionaries. The database consists of all allophonic (phonetically-conditioned) processes reported for the languages in the reference materials consulted. Allophonic processes were identified according to the following criteria: the presence of phonetic conditioning and/ or reported free variation, and indications by the author that the pattern is productive or widely applicable. Altogether, over 800 such processes were collected and coded. For each allophonic process, the segment(s) undergoing change, the outcome(s), and the conditioning environment(s) were coded according to traditional phonetic and phonological criteria (e.g. place of articulation, position in the syllable or word, etc.). Processes were usually taken directly from the reference as reported, but were then split or grouped together as necessary in order to reflect important differences or similarities in affected segments, outcomes, and/or conditioning environments. For example, if an author reports a pattern as three separate processes but these all affect sounds from the same natural class (e.g. voiceless stops) in the same way (e.g. spirantization) and in the same environment (e.g. intervocalic), we code this as one process with several affected sounds. Allophonic processes which were described as occurring optionally, in rapid or casual speech, or in particular sociolinguistic contexts were included, and these special conditions were noted. Roughly one- fourth of the processes were reported to occur in such contexts, supporting our assertion that the database represents sound change at a shallow time depth.

4.2 Results: Frequencies of weakening and strengthening processes

Here we use the AlloPhon database to test the oft-stated intuition that lenition is more common than fortition. As described above, we have defined lenition as a decrease in the degree of oral constriction of a consonant and fortition as an increase in the same. Specifically, we examine allophonic processes involving changes in manner of articulation among stops, affricates, fricatives, and approximants, and additionally processes of debuccalization and buccalization. There are 107 processes in AlloPhon which involve a decrease or increase in the degree of oral constriction of a consonant. The distribution of these processes can be found in Table 1. Consonant strengthening 277

Table 1: Processes in AlloPhon involving an increase or decrease in the degree of oral constriction of a consonant.

Process type N processes N languages with process type

Decreased constriction   Increased constriction  

These results show that, under our working definition of consonant strength, weakening is more common than strengthening, confirming the assertions of numerous researchers. Of the 107 processes examined here, 76 (71%) involve a decrease in oral constriction. Furthermore, processes of this type occur in 43 of the 81 languages sampled, while processes involving an increase in oral constriction occur in just 21 languages. (See the Appendix for a list of the languages in the sample marked according to whether weakening and/or strengthening processes are reported to occur.) Our results concur with those of previous typological studies of consonant strength changes, which also report more weakening than strengthening for the languages considered (Cser 2003; Lavoie 1996, Lavoie 2001). However, it is difficult to directly compare the broad results of these studies with our own, since the samples are limited to languages already known to have lenition or fortition, and properties such as changes in phonation and duration are also considered. By comparison, we observe a much higher relative rate of strengthening than Lavoie (1996): in her larger sample of 165 languages, 67 have processes resulting in decreased oral constriction, while only 16 have processes resulting in increased oral constriction. As discussed in Section 3, there is some disagreement in the literature as to whether lenition and fortition can be thought of as mirror-image processes. We address this question by examining the distribution of the particular process types represented by these 107 cases of weakening and strengthening in AlloPhon (Table 2). As stated above, if fortition and lenition are mirror-image processes, then we might expect to find fortition processes which simply run common lenition processes in the opposite direction, given the scale in (3), which attends only to the input and output of the process without regard for the context.6 While it is typically true in our data that for any given change in manner of articulation an

6 Determining which conditioning contexts constitute mirror images of one another is a more complicated undertaking which we do not formally attempt to do here, but we discuss 278 Joan Bybee and Shelece Easterday

Table 2: Comparison of lenition and fortition process types in AlloPhon.1,2

Lenition process type N processes Fortition process type N processes (N languages) (N languages) stop → affricate  ( lgs) affricate → stop — stop → fricative  ( lgs) fricative → stop  ( lgs) stop → approximant  ( lgs) approximant → stop  ( lgs) affricate → fricative  ( lgs) fricative → affricate  ( lgs) affricate → approximant — approximant → affricate  ( lg) fricative → approximant  ( lgs) approximant → fricative  ( lgs) debuccalization  ( lgs) buccalization  ( lgs)

1Recall that we have excluded from this analysis any process involving a change in manner of articulation or (de)buccalization in which the affected sound or outcome is a lateral approximant, trill, or flap/tap. The general distribution of the 37 such processes in our database is as follows: 13 involve the change of a stop, affricate, or fricative to a lateral approximant, trill, or flap/tap; 9 involve the change of a lateral approximant, trill, or flap/tap to a stop, affricate, or fricative; 15 involve the change of a lateral approximant, trill or flap/tap to a lateral approximant, trill, or flap/tap. None of the processes involved the change of lateral approximant, trill, or flap/tap to a central approximant or vice versa. 2Recall too that there is disagreement in the literature regarding whether the affrication of stops should be considered a weakening or a strengthening, although under the articulatory definition adopted here we consider it a weakening. If this particular process were analyzed as a strengthening instead, then in Table 2, the 14 stop > affricate processes would be classified as a fortition process type. The patterns in Table 1 would also change as follows: 62 processes of decreased constriction in 37 languages and 45 processes of increased constriction in 27 languages. If affrication of stops is excluded from the analysis altogether, there are 62 processes of decreased constriction in 37 languages and 31 processes of increased constriction in 21 languages. Note that regardless of the classification of stop affrication, overall rates of weakening are still higher than those of strengthening in AlloPhon. opposite process is attested (Table 2), there are some notable asymmetries in the distributions of these lenition and fortition processes. The lenition processes examined here most often involve a decrease in the degree of constriction of stops. By contrast, the distribution of fortition processes is skewed towards those involving an increase in the degree of constriction of approximants. While the change of a stop to an affricate accounts for roughly one-fifth of the lenition processes in the sample, the inverse of this process is not attested to occur in our sample of 81 languages. Similarly, 12/31 (39%) of the

important characteristics of the conditioning environments for the processes in each analysis that follows. Consonant strengthening 279 fortitions examined here involve the change of an approximant to a fricative, but its inverse accounts for only 8/76 (11%) of lenition processes. The relative rates and distributions of lenition and fortition processes presented here lend support to the idea that these paths of sound change differ in important ways and suggest that it is not entirely appropriate to consider them to be mirror images of one another. Next we examine the processes of fortition in greater detail in order to elucidate the ways in which this type of sound change differs from lenition.

4.3 Properties of strengthening processes

Having established that strengthenings are crosslinguistically less common than weakenings, and having quantified the magnitude of that difference, we now turn to a closer examination of the processes which increase the oral constriction of a consonant. We divide these 31 processes into three groups: those that involve the strengthening of an approximant, those that involve the strengthening of a fricative, and those in which glottal consonants gain oral articulation (buccalization).

4.3.1 Approximant strengthening

As shown in Table 2, the most common type of fortition in our survey is an increase in the degree of constriction of an approximant (these processes are listed in Table 3). As we have excluded lateral approximants from the present analysis, the approximants examined here are central approximants. Although central approximants at many different places of articulation occur in the consonant phoneme inventories of our language sample (see discussion in Section 4.5), in AlloPhon we only observe the strengthening of palatal and labial (or ‘labio-velar’) approximants or semi-vowels. These particular approximants closely resemble high vowels [i] and [u] in their articulation, and are referred to as glides when they function as consonants (Ladefoged & Maddieson 1996; Padgett 2008). Thus the most common strengthening processes in AlloPhon are cases of glide strengthening. These processes primarily affect palatal glides: nine of the 16 processes examined here affect only palatal glides, while just five affect only labial glides. There are two processes which affect glides at both palatal and labial places of articulation. As reported in Section 4.2, the most common outcome for the strengthening of an approximant in our data is for it to become a fricative articulation. Rarer outcomes include an affricate outcome, pre-stopping or pre-nasalization, and a nasal stop outcome. Palatal glides tend to strengthen into consonants which are 280 Joan Bybee and Shelece Easterday

Table 3: Approximant strengthening processes in AlloPhon.

Language Process

Palaung /j/ > slightly fricated preceding high vowels and /ə/ (Austro-Asiatic) (Shorto : ). Tinrin /j/ > articulated with more friction preceding a high (Austronesian) front vowel (Osumi : ). Carib /j/ > [ʑ] in the environment of a high front vowel (Hoff (Cariban) : ). Apinayé /j/ > [ʑ] when it is the simple onset of a stressed (Nuclear-Macro-Je) syllable (Cunha de Oliveira : ). Selepet /j/ > [zj] word-initially preceding a front vowel (Nuclear Trans-New Guinea) (McElhanon : ). Lahu /j/ > [ ʝ] preceding a front vowel (Matisoff : ). (Sino-Tibetan) Lahu /j/ > [z] preceding a high central vowel (Matisoff (Sino-Tibetan) : ). Jivaro /w/ > [β ~ v] contiguous to a high front vowel (Turner (Chicham) : ). Apinayé /w/ > [v] when it is a simple syllable onset (Cunha de (Nuclear-Macro-Je) Oliveira : ). Selepet /w/ > [β] word-initially preceding a front vowel (Nuclear Trans-New Guinea) (McElhanon : –). Chepang /w/ > fricated adjacent to front vowels (Caughley (Sino-Tibetan) : ). Cocama /w/ may > [β ~ v] preceding high front vowels (Faust & (Tupian) Pike : ). Apinayé /j/ > [dʒ] in a word-final coda when preceding a vowel- (Nuclear-Macro-Je) initial word (Cunha de Oliveira : ). Pech /j/ > [dj], /w/ > [ɡw] often, especially when word- or (Chibchan) morpheme-initial (Holt : ). Dan /j/ > [nȷ],̃ /w/ > [ŋw]̃ preceding a nasalized vowel (Mande) (Bearth & Zemp : ). Trumai /j/ > [ ɲ] preceding a vowel-nasal sequence (isolate) (Guirardello : ).

also produced in the general palatal(ized) region (6) but a dental/alveolar outcome of [z] also occurs (7). The Lahu example in (7) is also the only process in this set that involves a significant shift in place of articulation. Labial glides strengthen to bilabial or labiodental fricatives (8). Consonant strengthening 281

(6) Apinayé (Nuclear-Macro-Je) The palatal glide /j/ is realized as a voiced alveolo-palatal fricative [ʑ]in simplex onsets of stressed syllables. /ajet/ [aˈʑet] ‘to be suspended on a surface’ (Cunha de Oliveira 2005: 58–59)

(7) Lahu (Sino-Tibetan) Preceding high central vowel /ɨ/, a palatal glide is realized as a voiced alveolar fricative. /jɨ21/ [zɨ21] ‘sleep’ (Matisoff 1973: 6)

(8) Cocama (Tupian) Labial glide /w/ has freely fluctuating allophones [w ~ β ~ v] preceding front vowels. /tsawiti/ [tsawiti] ~ [tsaβiti] ~ [tsaviti] ‘to answer’ (Faust & Pike 1959: 16)

The glide strengthenings in AlloPhon show a great deal of coherence in their conditioning environments. Nearly all of these processes are found in one of two environments: preceding a high and/or front vowel (in which case the glide is typically additionally in syllable-initial position), or a domain-initial position, such as a word or syllable onset, regardless of the following vocalic context. The two processes from Selepet are conditioned by a combination of the high and/or front vowel context and the word-initial context. As mentioned above, our survey of increased constriction excluded processes occurring adjacent to a consonant, because a neighboring consonant, with its associated oral constriction properties, is likely to be the main conditioning factor. A process in Apinayé, not listed in Table 3, caught our attention. This process leads to glide strengthening in the second position in a syllable onset (9). Most theories of the syllable would not predict a strengthening in what should be a relatively weak position. 282 Joan Bybee and Shelece Easterday

(9) Apinayé (Nuclear-Macro-Je) /akje/ [aˈkze] ‘to open a hole (on a surface)’ (Cunha de Oliveira 2005: 59)

Though rare, such processes have been discussed in the recent literature on Tswana (Bateman 2010) and Kirundi (Kochetov 2016) (both Bantu), and Greek dialects (Baltazani et al. 2016). Sound changes involving a strengthening in this position are known from Romance where Latin plōrāre ‘to cry’ became Portuguese chorar via a series of changes whereby the second-position /l/ became /j/ (perhaps via a palatalized lateral) and then strengthened (see also Bateman 2010). While we will not treat such changes here, we observe that the adjacent consonant likely plays a role in the increased constriction, and that the underlying mechanisms discussed in Section 5 may be applicable to such cases.

4.3.2 Fricative strengthening

Processes of fricative strengthening are half as frequent in AlloPhon as processes of approximant strengthening. We list these processes in Table 4. Interestingly, the fricative strengthening processes in our sample largely favor the same places of articulation as approximant strengthening. Of the eight processes, six affect fricatives in the palatal (here palato-alveolar) and labial regions and have affricate or stop outcomes in those same regions. While the process from Kanuri affects an alveolar fricative, it has a palato-alveolar outcome. The only exception to this general pattern is the Kadiwéu process, in which a uvular fricative is reported to strengthen to a stop. Like the glide strengthening processes examined earlier, many of the fricative strengthening processes are conditioned by domain position (syllable or word onset); however, the high and/or front vowel environment is not a strong factor here, conditioning only one process. Additionally, the environments represented here include syllable-final position and adjacent back vowels. In terms of the place of articulation of affected segments, outcomes, and to a lesser extent, conditioning environments, fricative strengthening processes share much in common with glide strengthening processes. However, it is important to note that in some cases, the fricative strengthening processes reported in the synchronic descriptions may not reflect the diachronic directionality. Consonant strengthening 283

Table 4: Fricative strengthening processes in AlloPhon.

Language Process

Garifuna /ʃ/ > [tʃ] in stressed syllables, and in all positions in (Arawakan) deliberate speech (Taylor : ). Pech /ʃ/ > [tʃ] in syllable onset for many, especially younger, (Chibchan) speakers (Holt : ). Sheko /ʒ/ has free variant [dʒ] (Hellenthal : ). (Dizoid) Kanuri /s/ > [dʒ] following a sonorant and preceding a mid or (Saharan) high front vowel (Cyffer : ). Sheko /ʒ/ has free variant [ɟ] (Hellenthal : ). (Dizoid) Kadiwéu /ʁ/ optionally > [ɢ] in word-initial position (Sandalo (Guaicuruan) : ). Koiari /ɸ/ may > [p] word-initially preceding back vowels (Koiarian) (Dutton : ). Ningil /ɸ/ may > [p] word-initially and -medially (Manning & (Nuclear Torricelli) Saggers : ). Oksapmin /ɸ/ > [p] syllable-finally (Loughnane : ). (Nuclear Trans-New Guinea)

The Sheko processes, in which a palato-alveolar fricative varies with an affricate and a palatal stop, respectively, are described as being cases of unconditioned free variation: bāʒà [bāʒà]~[bādʒà]~[bāɟà],‘work’ (Hellenthal 2010: 86). Although the author chooses the fricative as the phoneme label, the lack of a specific conditioning environment leaves open an interpretation of a decrease in constriction, rather than an increase. The palato-alveolar fricative strengthening process in Pech may not reflect a typical sound change so much as recent extensive contact with Spanish, which has [tʃ] but not [ʃ] (Holt 1999: 16). For some of the fricative > stop strengthenings, a compelling case could be made for an opposite diachronic directionality. Although the Kadiwéu process is reported as the strengthening of a uvular fricative, the author reconstructs the proto-phoneme as a uvular stop in Proto-Guaicuruan, suggesting a historical weakening. Doubts also arise with respect to the reports of bilabial fricatives becoming stops. For instance, in both Koiari and Oksapmin, there is no /p/ phoneme, suggesting a possible historical weakening of this crosslinguistically frequent consonant. Indeed, Loughnane and Fedden (2011) propose that Oksapmin /ɸ/ derives historically from the collapse of /*p/ and /*f/ into a single phoneme in Proto-Oksapmin. Thus it appears that the 284 Joan Bybee and Shelece Easterday evidence for fricatives strengthening to stops is much weaker than that for glides strengthening to obstruents.

4.3.3 Buccalization

Theprocesswearecalling‘buccalization’ (as the opposite of debuccalization) occurs when a glottal consonant gains an oral constriction. In AlloPhon, all six processes of buccalization affect glottal fricatives. These processes are listed in Table 5.

Table 5: Buccalization processes in AlloPhon.

Language Process

Tinrin /h/ > [ç] preceding high front vowels (Osumi : –). (Austronesian) Tinrin /h/ > [ɸ] before high back and central vowels (Osumi : ). (Austronesian) Norwegian /h/ > sometimes > [ç] adjacent to front vowels (Vanvik : ). (Indo-European) Norwegian /h/ sometimes > [x] adjacent to back vowels (Vanvik : ). (Indo-European) Maidu /h/ > [ç] with minimum friction preceding high front vowel (Shipley (Maiduan) : ). Maidu /h/ > [χ] with minimum friction preceding mid front vowel and high (Maiduan) central vowel (Shipley : ).

The buccalization processes consist of three pairs of processes from three languages. In each case, buccalization has two different outcomes depending on the vocalic environment. First, glottal fricatives gain palatal constriction adjacent to high front or front vowels. These processes are complemented in each language by processes in which glottal fricatives gain oral constrictions at bilabial, velar, or uvular places of articulation in adjacency to various other vowels. Although buccalization is a rare process in our language sample, it is interesting that there is considerable overlap between the conditioning environments and outcomes of these processes and those of the most common increased constriction process, glide strengthening. Now that we have presented all of the cases of strengthening considered in our study and summarized their characteristics, we turn to a brief analysis of the characteristics of the weakening processes in AlloPhon. Consonant strengthening 285

4.4 Properties of weakening processes

While we do not list each of the weakening processes here, we present general analyses of their place of articulation and conditioning properties in order to provide a point of comparison with the strengthening processes. In Table 6, the 76 decreased constriction processes in AlloPhon are distributed according to the place of articulation of the affected consonant(s).

Table 6: Lenition processes in AlloPhon distributed according to the place of articulation of the affected consonant(s). * ‘Palatal region’ includes palatal, palato-alveolar, alveolo-palatal, and (in one process) retroflex places of articulation.

Place of articulation → labial alveolar/ palatal velar uvular multiple dental region* places Process type ↓ stop → affricate () –– stop → fricative ()  stop → approximant ()  –  –  affricate → fricative () –– –– – fricative → approximant () –  –– debuccalization () – – 

Whereas strengthening processes tend to affect palatal and labial consonants and/or have outcomes at those places of articulation, a more diverse range of places of articulation is represented in the weakening processes. Processes involving the change of a stop to a fricative, in particular, occur at every place of articulation examined here. In fact, it is common in our language sample for the same spirantization process to affect stops at multiple places of articulation, as shown for Basque in (10a–c):

(10) Basque (isolate) Voiced stops /b d ɡ/ are phonetically realized as fricatives [β ð ɣ] intervocalically. (a) /abere/ (b) /edan/ (c) /iɡeri/ [aβere] [eðan] [iɣeri] ‘animal’‘to drink’‘swimming’ (Saltarelli et al. 1988: 266–267) 286 Joan Bybee and Shelece Easterday

The only type of weakening examined here that has a strong tendency to affect consonants in the palatal region is the change from an affricate to a fricative. These processes always involve the change of a palato-alveolar, alveolo-palatal, or retroflex affricate to a fricative at the same place of articulation, as seen in Uyghur (11). The predominance of the palatal region in these process types may be reflective of the general high frequency of palato-alveolar affricates, as compared to affricates at other places of articulation, in phoneme inventories crosslinguistically (Maddieson 1984).

(11) Uyghur (Turkic) Palato-alveolar affricates are fricativized whenever they are syllable-final. /wædʒ/ [wæʒ] ‘a~the key’ (Hahn 1991: 89)

While only one of the strengthening processes examined in previous sections involved a significant shift in place of articulation, we find that 14 of the weakening processes involve place of articulation shift. Nearly all such processes involve a consonant at the palatal region as an affected sound (3 processes) or as an outcome (10 processes). In the most common such process type, a velar stop or fricative weakens to a palatal glide (6 processes; example 12).

(12) Slave (Athabaskan-Eyak-Tlingit) Before a front vowel, /ɣ/ is pronounced both [ɣ] and [j]. /ʔeɣéː/ [ʔeɣéː]~[ʔejéː] ‘egg’ (Rice 1989: 33)

We will not go into further detail about such processes here, but we observe that the relative rates of shifts in place of articulation constitute another interesting asymmetry between the strengthening and weakening processes in our data. In Table 7, we present an analysis of the conditioning environments of the decreased constriction processes in AlloPhon. The weakening processes show a diverse range of conditioning environments as compared to the increased constriction processes. However, some conditioning environments are more characteristic of certain process types than others. Consonant strengthening 287

Table 7: Lenition processes in AlloPhon distributed according to the environment conditioning their occurrence. Note that some processes are conditioned by a combination of environments.

Conditioning inter- syllable- or high and/or back and/or all other or environment → vocalic word-final front vowels round vowels unspecified

Process type (N processes) ↓ stop → affricate () ––    stop → fricative ()       stop → approximant ()  – – affricate → fricative () –   fricative →   –– approximant () debuccalization ()  ––

Although the intervocalic environment is often described as a prototypical conditioning factor for lenition processes, in our data it is the dominant conditioning environment only for processes involving a change of a stop to a fricative or a stop to an approximant. The specific vocalic environment is relevant in conditioning two process types. In processes involving the change of a fricative to an approximant, both high and/or front vowel environments and back and/or round vowel environments are equally likely to be conditioning factors. In processes involving the change of a stop to an affricate, it is the high and/or front vocalic environment which is most likely to trigger the process (13).

(13) Nakanai (Austronesian) Voiceless alveolar stop /t/ may be realized as [ts] before /i/. /ɛtila/ [ɛtila] ~ [ɛtsila] ‘mother’ (Johnston 1980: 249)

It is interesting to note that stop affrication is often conditioned by a high front vowel, and also frequently affects coronal consonants. In this regard it resem- bles assimilation perhaps more than weakening per se. Note that the high front vowel conditioning also occurs for some of the glide strengthening processes, suggesting they also may have causes similar to those operative in assimilation processes (Bhat 1978; Bateman 2010). Future research could reveal more similarities between strengthening and assimilation. 288 Joan Bybee and Shelece Easterday

4.5 Discussion

Having analyzed the processes in AlloPhon which involve a change in the degree of oral constriction of a consonant, we can now identify some important characteristics of consonant strengthening and weakening:

Characteristics of strengthening processes 1. The most common process type is the increased constriction of central approximants, particularly glides. 2. Strengthening processes typically affect palatal or labial consonants (usually glides), and/or have outcomes at those places of articulation. 3. The conditioning environments of strengthening processes tend to include high and/or front vowels or domain-initial positions.

Characteristics of weakening processes 1. The most common process type is the decreased constriction of stops, particularly with a fricative outcome. 2. Weakening processes affect consonants at a diverse range of places of articulation. 3. The conditioning environments of weakening processes are diverse, with intervocalic and specific vocalic contexts conditioning different kinds of processes.

Our results show that, under the definition of consonant strength we have adopted, strengthening and weakening are not simply mirror image processes, but differ in several important ways. Overall, we find that the kinds of strengthenings that emerge from our data — glide strengthening, fricative strengthening, and buccalization — are quite coherent in terms of the place of articulation of the affected sounds and outcomes and their conditioning environments. By comparison, the weakenings, while sometimes showing coherence within process types, cover quite a wide range of conditioning environments and outcomes. This finding is in conflict with Cser (2003: 83), who states that “while certain weak generalisations can be made about the environments conducive to lenition, it is not possible to assign typical environments to fortition” (though note that Cser examines a much broader range of processes than we do here, including phonation changes and processes involving liquids). Our findings suggest that strengthening tends to be less about increases in magnitude in general and more about the particular places of articulation involved: glide strengthening, fricative strengthening, and buccalization all share palatal and labial articulations in common. It is striking that even the Consonant strengthening 289 reported cases of fricative strengthening which are open to a diachronic weakening interpretation happen to occur at these same places of articulation. This observation raises the question of whether the languages in the sample have fricatives or central approximants at other places of articulation. Examining the consonant inventories of the languages in Allophon, we find that the most common places of articulation for oral fricatives are dental/alveolar (68 languages) and labiodental (36 languages). Although one fricative strengthening process affects an alveolar fricative (in Kanuri), the processes examined here generally do not affect the most cross-linguistically frequent places of articulation for fricatives. Regarding central approximants, we find that these consonants overwhelmingly occur at palatal and labial (specifically bilabial or labio-velar) places of articulation in AlloPhon. However, there are eleven languages with central approximants at other places of articulation, including labiodental, alveolar, retroflex, velar, and uvular places. While these approximants are not very frequent in the sample, it is interesting that no cases of strengthening are reported for them in the sources consulted. Our examination of processes involving increased oral constriction does support the common assumption that strengthenings are less common than weakenings, and that fortition is not on par with lenition in its generality and reach. However, our data also indicate that these processes may not be as vanishingly rare as some assertions in the literature would suggest. As noted above, such processes occur in roughly one-fourth of the languages in our sample, and one particularly common type of fortition, glide strengthening, occurs in 12 of the 81 languages sampled (15%). Outside our language sample, cases of synchronic glide strengthening in high and/or front vocalic and domain-initial environments are well-documented in many languages from diverse families and geographical regions. We list some of those languages known to have palatal glide strengthening in Table 8, and some of those languages known to have labial glide strengthening in Table 9. Note in the following tables that when a glide is said to strengthen “preceding a high and/or front vowel,” the glide is also typically in syllable-initial position. On the other hand, “domain-initial” conditioning indicates that the process occurs when a glide is in a domain- (typically word- or phrase-, but sometimes syllable-) initial position, regardless of the vocalic environment. Historical processes of glide strengthening are also known from well-documented languages, such as those in the Romance family. For instance, the Latin initial semi-vowel in iustus ‘just, proper’ evolved over time into [ʒ] in Portuguese justo (Mattoso Câmara Jr 1972). In the results from AlloPhon presented in Section 4.3.1 and the group of languages represented in Tables 8 and 9, strengthening of palatal glides is more frequently reported than strengthening of labial glides. This is likely related to the fact that palatal glides occur in consonant phoneme inventories more often 290 Joan Bybee and Shelece Easterday

Table 8: Other languages with palatal glide strengthening.

Family Language Reference Environment

preceding a high domain- and/or front vowel initial

Atlantic-Congo Akan Welmers (: ) ✓ Austronesian Atayal Huang (: ) ✓ Barbacoan Awa Pit Curnow (: ) ✓ Chapacuran Wari’ Everett and Kern ✓✓ (: ) Finisterre-Huon Yau Sarvasy (: ) ✓✓ Furan Fur Jakobi (: ) ✓ Indo-European Argentinean Harris and Kaisse ✓ Spanish () Mongolic Santa Field (: ) ✓ Nuclear Trans-New Kainantu Loving (: ) ✓ Guinea Otomanguean Pinotepa Bradley (: ) ✓ Mixtec Saharan Beria Jakobi and Crass ✓ (: ) Skou Barupu Corris (: ) ✓ Tucanoan Guanano Stenzel (: ✓ –) Tungusic Ewen Kim (: ) ✓

than labial glides. In AlloPhon (81 languages), palatal glides occur in 68 languages, while labial glides occur in 61 languages.7 Palatal glide strengthening occurs in 9/68 languages with palatal glides (13%), while labial glide strengthening occurs in 7/61 languages with labial glides (11%). There is not strong evidence in our data that palatal glides are more likely to strengthen than labial glides, given the presence of both types of glides in a language. Finally, let us note that in our systematic survey (AlloPhon), the geographical distribution of languages with strengthening processes is not even. The highest concentration of such languages is in South America: a remarkable eight of the ten languages sampled in this region are reported to have strengthening processes. The regions with the next highest rates of strengthening in the

7 These proportions are in line with those presented in Maddieson’s (1984) survey of 317 languages, in which palatal and labio-velar glide phonemes occur in 86.1% and 75.7% of languages, respectively. Consonant strengthening 291

Table 9: Other languages with labial glide strengthening.

Family Language Reference Environment

preceding a high domain- and/or front vowel initial

Atlantic-Congo Akan Welmers (: –) ✓ Austroasiatic Pacoh Alves (: ) ✓ Austronesian Māori Bauer (: ) ✓ Chicham Aguaruna Overall (: ) ✓ Mixe-Zoque Tlahuitoltepec Romero-Méndez (: ✓ Mixe –) Mongolic Santa Field (: ) ✓ Otomanguean Pinotepa Bradley (: ) ✓ Mixtec Pano-Tacanan Ese Ejja Vuillermet (: ) ✓ Siouan Hidatsa Park (: –) ✓ Skou Barupu Corris (: –) ✓ Tucanoan Guanano Stenzel (: ) ✓ Uru-Chipaya Chipaya Cerrón Palomino (: ) ✓

sample are Australia and New Guinea (4/16 languages) and Southeast Asia and Oceania (4/19 languages). By contrast, only one of the ten Eurasian languages sampled was reported to have strengthening processes in AlloPhon (though note, as we state above, that many historical cases of strengthening are known in this region). We suggest that some of the assumptions in the literature and findings of previous typological studies regarding the relative frequency of strengthening processes may partially reflect a common overrepresentation of the synchronic patterns of European languages and a common underrepresenta- tion of the patterns of languages from other regions, including South America and New Guinea.

5 An articulatory basis for strengthening

In Section 3 we mentioned briefly the view that the most common types of sound change — lenition and assimilation — can plausibly be attributed to the automatization of production. That is, given highly practiced sequences of sounds, the articulators tend towards articulations that are more efficient considering all the physical constraints of the motor system and the particular articulators used. Of course, our understanding of the movements of the articulators from one 292 Joan Bybee and Shelece Easterday position to another is still in its infancy, but nevertheless examining this system seems like a reasonable path to understanding sound change more fully. As mentioned earlier, any type of increase in constriction stands as a potential counterargument to the general automatization hypothesis. For that reason, we have isolated such examples to examine their properties. We found that certain places of articulation — palatal and labial — are the sites for increases in constriction and that glides are more likely than any other consonant type to undergo strengthening. Now the question arises as to whether there is an articulatory account of the sound changes in question and whether it can be considered to result from the automatization of production. Speech production is a well-practiced motor behavior. Observations of high frequency words and phrases show reductions in duration, as well as reductions in the extent of gestural displacement of the articulations involved (Bybee et al. 2016; Mowrey & Pagliuca 1995). In words at all levels of frequency, Lavoie (2001) finds that medial consonants are shorter in duration, which may result in the reduction in magnitude of the articulatory movement in these consonants more that in initial ones. Evidence such as this shows that automatization of sequences of speech sounds leads in some contexts to reduction in temporal duration and in gestural displacement. The question addressed in the current section, then, is whether the existence of strengthening processes (evidenced by increased constriction presumably resulting from increased magnitude of an articulatory movement) necessarily falsifies the theory that sound change arises from the automatization of production. Speech production is highly complex, with many factors coming into play— the size, shape and positioning of the articulators, the distance and direction of a movement, and the effect of surrounding articulations. Here we sketch a possible account of strengthening based on research into other types of motor behavior, in the hopes of suggesting a path for future research. Our main point follows from Pouplier’s proposal that a shorter trajectory of movement may not be the most efficient. Pouplier (2012: 153) argues that “distance moved by an articulator is too narrow a concept when it comes to movement optimization in a biomechanical system as complex as the vocal tract.” One of her examples concerns the velar loop, a phenomenon by which a velar stop in a back vowel context [ugu] moves forward in a looping motion that appears to make distance traveled longer than it needs to be. Pouplier points out, following Perrier et al. (2003), that the forward movement is a consequence of the orientation and other aspects of the tongue’s muscular anatomy. Thus, “an increase in distance travelled is not necessarily tantamount to an increase in energy expenditure” (2012: 154, emphasis in original). For our purposes such a case demonstrates that what is easy or efficient in speech production depends Consonant strengthening 293 upon many factors, including the size, shape and orientation of the muscles in the active articulators as well as the position of the passive ones. Such findings are relevant to our study, because the strengthening processes we have identified seem to be cases in which the articulator travels a greater distance, yet there might be a reason that this greater distance is more efficient. We point to a finding from research on hand movements that might yield a clue to the motivation behind glide strengthening, though it has to be borne in mind that such research involves a very different set of physical structures, and hand movements not involved in speech might have different properties than vocal tract movements used for articulating speech. In the motor behavior research, sequences of hand movements have been studied to test the effect of practice on gains in efficiency. In Sosnik et al. (2004), subjects were asked to connect four target points with a pen as accurately and rapidly as possible upon hearing an auditory cue. The subjects practiced the same sequence repeatedly over five days. With practice, there were robust changes in performance in all participants. While subjects began with straight lines and slowed or stopped movement at target points, after practice the lines became curvilinear, and the stopping at target points was eliminated. Despite the increased length of the lines drawn, the time it took to draw them was decreased. Figure 1 shows the types of differences observed with practice.

Figure 1: Changes occurring with practice in lines drawn to connect target points. From Kapatsinski (2018), based on Sosnik et al. (2004).

Presumably, the reason the curved line continues beyond the target is the inertia in the forward movement. It is more efficient to extend beyond the target, slow gradually and curve gradually, than to stop and make an abrupt change of direction. This follows from another feature of the longer curved trajectories, which concerns changes in velocity. While before practice, slowing occurred at the target points (and elsewhere), the highly practiced trajectory slows at the point which corresponds to the point of local maximum curvature. That is, at the point at which a change of direction takes place, the movement slows down. 294 Joan Bybee and Shelece Easterday

Now, following Kapatsinski (2018), let us apply this finding about movement changes to speech sounds. Kapatsinski observes “[t]his means that certain seemingly nonreductive changes can nonetheless be the result of automatizing articulation” (Kapatsinski 2018: 241). Given that a glide is in constant motion (Catford 1988; Chitoran 2003), we assume that [j] or [w] between two vowels has a curved trajectory. At the point of maximum curvature (which is also the maximum constriction) the movement slows because a change in direction is necessary. There could be some inertia that continues the upward movement to produce the glide, taking it higher than is really necessary, and the slowing gives the maximum curve some duration. Together these could lead to a position that creates frication and enough duration in the constriction to create a fricative. This general principle must be applied to palatals and labials in different ways. Recasens and colleagues (Recasens 2014; Recasens & Espinosa 2006, 2009) find that bulkier articulators (such as the tongue body) are less influenced by surrounding articulations and more likely to produce changes in adjacent articulations. In their comparisons of different articulations, Recasens and Espinosa find that the high front vowel and palato-alveolar stops and fricatives are more constrained than other lingual articulations, such as alveolar and velar consonants. They note that the production of palato-alveolar stops “involves a larger contact surface and a more sluggish articulator, i.e. the tongue dorsum” than other articulations and that “the raising and fronting of the tongue dorsum blocks the coarticulatory activity of other tongue regions” (Recasens & Espinosa 2009: 2288–2289). As bulky articulators experience the effects of inertia more than smaller, more agile ones, such as the tongue tip, the size of the articulator partially determines the shape of the curve resulting from its movement in space. A bulkier articulator would take more time to slow down and change direction than a more agile one. That would mean that the maximal point in the curve might be higher in the vocal tract and the duration of the curve longer at that point, increasing the chances of creating a fricative. For labial articulations, the relevant fact may be that two active articulators are involved—the upper and lower lip. Neither is as bulky as the tongue body but with two active articulators there are two movement trajectories; for a labial glide both articulators would move in an arc with the points of maximum curvature approaching one another. As in the case of the palatal glide, over- shooting the target and slowing at the point of maximum curvature could produce a constriction with frication noise. We have less information about the rarer changes by which glottal fricatives acquire an oral articulation due to surrounding vowels (buccalization), but we can observe that the glottal fricative acquires an oral constriction corresponding Consonant strengthening 295 to the articulatory characteristics of an adjacent (usually following) vowel. Perhaps in these cases, the increased constriction proceeds quite similarly as we have described for the palatal and labial glides, with increased duration and greater oral constriction resulting from the movement trajectory between the vowels abutting the glottal consonant. Given this proposal by which automatization may lead to the ‘overshoot’ of the target, the question arises as to why fricatives do not often change to stops (or affricates) by the same procedure. The answer is that fricatives differ from glides, because, as Ladefoged and Maddieson point out, they require that “an exactly defined shape of the vocal tract has to be held for a noticeable period of time” (1996: 138) (see also Geumann et al. 1999; Mooshammer et al. 2006.) That is, rather than a curved path, the maximal displacement point for the fricative is held constant. This would require slowing of movement before the target point is reached, eliminating the inertia that might pull the movement beyond the target. A further point made by Sosnik et al. (2004) which echoes proposals in linguistics by Mowrey and Pagliuca (1995), Bybee (2002), and Kapatsinski (2018), is that practice leads to the establishment of longer chains of movements as units of access and production, which in the case of language would range from sequences of segments and syllables to word groups. Sosnik and colleagues demonstrate that these new automatized movements can be extended to new situations. Applying this finding to sound change, a new automatized movement sequence, first produced in a high frequency form, can perhaps be accessed and used in novel forms, providing a mechanism by which a sound change progresses from one lexical item to another.

6 Conclusion

This paper addressed a presumed asymmetry in the inventory of known sound changes: the prevalence of consonant weakening changes over strengthening changes. A systematically structured crosslinguistic database of phonological processes allowed us to quantitatively substantiate this asymmetry, and also allowed us to study the properties of the two potentially opposite types of changes. The results showed that strengthening (defined as an increase in the degree of oral constriction) is not the simple opposite of weakening (a decrease in degree of oral constriction), but rather the two types differ in the places of articulation of the segment types affected and the range of conditioning environments involved. Strengthenings are much more restricted in the types of sounds affected — primarily palatal and labial glides — and in their conditioning 296 Joan Bybee and Shelece Easterday environments than are weakening processes, which target stops more than other segment types and all places of articulation. The ultimate goal of any study of sound change is to provide an explanation for observed tendencies. Our approach has been to consider whether or not a theory of sound change as the result of the automatization of production is falsified by the existence of fortition, or whether apparent fortition can also be seen as a result of the automatization of motor patterns. Given that the occurrence of the two directions of change are not randomly distributed in the languages of the world, but that strengthenings are highly restricted, an exten- sion of the automatization scenario to these processes seems possible. Given the complexity of the articulatory and auditory systems, a full account of why glide strengthening occurs more often than other potential types of consonant strengthening is not possible based on current knowledge. However, we have pointed tentatively to properties of the palatal and labial articulators as making them more susceptible to certain types of change. In addition, we have considered briefly the possibly relevant factor of how movement is optimized when a change in direction is required. These two factors, among other important physiological, aerodynamic, cognitive, and social con- siderations, may play into a full explanation of the very restricted strengthening processes uncovered in our crosslinguistic survey. By viewing the properties of the speech production apparatus as part of a general neuromotor system, we support an alternative view of the notion of ‘ease of articulation’. In this view, variation in production as found in casual speech, or codified in sound change, is neither lazy nor sloppy, but rather the outcome of more general cognitive and motor mechanisms that reshape highly practiced behavior. Given that any particular sound change is necessarily language-specific, these universal mechanisms of automatization apply within a complex adaptive system that is also responsive to initial conditions (phonetic practices already established), repeated exposure to other speakers’ phonetic patterns, the speaker’s aim to sound like others of her/his group, the lexical distribution of segments, and other factors. Thus ‘ease of articulation’ is molded within a particular social group as a response to many different factors. Even so, the patterns across languages are still clear enough to allow us to identify factors that apply across languages, such as the phonetic factors discussed here. The proposals about the nature of sound change we have made here are only possible because we have based them on a systematic survey of phonological processes in a diverse sample of languages selected to be maximally unrelated genealogically. This method allows us to go beyond the phonologists’ intuitions about what is common or uncommon, possible or impossible, to a greater understanding of the general phenomena to be explained. Consonant strengthening 297

References

Alves, Mark J. 2006. A grammar of Pacoh: A Mon-Khmer language of the central highlands of Vietnam (Pacific Linguistics 580). Canberra: Pacific Linguistics, Research School of Pacific and Asian Studies, the Australian National University. Baltazani, Mary, Evia Kainada, Anthi Revithiadou & Nina Topintzi. 2016. Vocoid-driven processes: Palatalization and glide hardening in Greek and its dialects. Glossa: A Journal of General Linguistics 1(23). 1–28. Bateman, Nicoleta. 2010. The change from labial to palatal as glide hardening. Linguistic Typology 14(2/3). 167–211. Bauer, Winifred. 1999. Maori. London/New York: Routledge. Bearth, Thomas & Hugo Zemp. 1967. The phonology of Dan (Santa). Journal of African Languages 6. 9–29. Bhat, D. N. S. 1978. A general study of palatalization. In Joseph H. Greenberg, Charles A. Ferguson & Edith A. Moravcsik (eds.), Universals of human language, vol. 2: Phonology, 47–92. Stanford: Stanford University Press. Bickel, Balthasar. 2008. A refined sampling procedure for genealogical control. Sprachtypologie Und Universalienforschung 61. 221–233. Blevins, Juliette. 2004. Evolutionary phonology: The emergence of sound patterns. Cambridge: Cambridge University Press. Blevins, Juliette. 2015. Evolutionary phonology: A holistic approach to sound change typology. In Patrick Honeybone & Joseph Salmons (eds.), The Oxford handbook of historical phonology, 485–500. Oxford: Oxford University Press. Bradley, C. Henry. 1970. A linguistic sketch of Jicaltepec Mixtec. Norman: Summer Institute of Linguistics of the University of Oklahoma. Brandão de Carvalho, Joaquim, Tobias Scheer & Philippe Ségéral (eds.). 2008. Lenition and fortition (Studies in Generative Grammar 99). Berlin: Mouton de Gruyter. Browman, Catherine & Louis Goldstein. 1991. Gestural structures: Distinctiveness, phonological processes and historical change. In Ignatius Mattingly & Michael Studdert-Kennedy (eds.), Modularity and the motor theory of speech perception, 313–339. Hillsdale, NJ: Lawrence Erlbaum. Browman, Catherine & Louis Goldstein. 1992. Articulatory Phonology: An overview. Phonetica 49. 155–180. Brown, Esther L. & William D. Raymond. 2012. How discourse context shapes the lexicon: Explaining the distribution of Spanish f- / h- words. Diachronica 92(2). 139–161. Buizza, Emanuela & Leendert Plug. 2012. Lenition, fortition and the status of plosive affrication: The case of spontaneous RP English /t/. Phonology 29(1). 1–38. Bybee, Joan. 2000. The phonology of the lexicon: Evidence from lexical diffusion. In Michael Barlow & Suzanne Kemmer (eds.), Usage-based models of language,65–85. Stanford, CA: CSLI Publications. Bybee, Joan. 2001. Phonology and language use. Cambridge: Cambridge University Press. Bybee, Joan. 2002. Sequentiality as the basis of constituent structure. In T. Givón & Bertram F. Malle (eds.), The evolution of language from pre-language, 107–132. Amsterdam: John Benjamins. Bybee, Joan. 2006. Language change and universals. In Ricardo Mairal & Juana Gil (eds.), Linguistic universals, 179–194. Cambridge: Cambridge University Press. 298 Joan Bybee and Shelece Easterday

Bybee, Joan. 2012. Patterns of lexical diffusion and articulatory motivation for sound change. In Maria-Josep Solé & Daniel Recasens (eds.), The initiation of sound change: Perception, production and social factors, 211–234. Amsterdam/Philadelphia: John Benjamins. Bybee, Joan & Clay Beckner. 2015. Emergence at the crosslinguistic level: Attractor dynamics in language change. In Brian MacWhinney & William O’Grady (eds.), The handbook of language emergence, 181–200. Chichester, UK: Wiley-Blackwell. Bybee, Joan, Richard File-Muriel & Ricardo Napoleão de Souza. 2016. Special reduction: A usage-based approach. Language and Cognition 8(3). 421–446. Bybee, Joan L., Revere D. Perkins & William Pagliuca. 1994. The evolution of grammar: Tense, aspect and modality in the languages of the world. Chicago: University of Chicago Press. Catford, J. C. 1988. A practical introduction to phonetics. Oxford: Clarendon Press. Caughley, Ross Charles. 1982. The syntax and morphology of the verb in Chepang (Pacific Linguistics B 84). Canberra: Australian National University. Cerrón Palomino, Rodolfo. 2006. El chipaya o la lengua de los hombres del agua. Lima: Pontificia Universidad Católica del Perú. Chitoran, Ioana. 2003. Gestural timing and the glide percept in Romanian. Proceedings of the 15th International Congress of the Phonetic Sciences. 3013–3016. Corris, Miriam. 2005. A grammar of Barupu: A language of Papua New Guinea. Sydney: University of Sydney dissertation. Cser, András. 2003. The typology and modelling of obstruent lenition and fortition processes. Budapest: Akadémie Kiadó. Cunha de Oliveira, Christiane. 2005. The language of the Apinajé people of Central Brazil. Eugene: University of Oregon dissertation. Curnow, Timothy J. 1997. A grammar of Awa Pit (Cuaiquer): An indigenous language of south- western Colombia. Canberra: Australian National University dissertation. Cyffer, Norbert. 1998. A sketch of Kanuri. Köln: Rüdiger Köppe Verlag. Dryer, Matthew. 2000. Counting genera vs. counting languages. Linguistic Typology 4. 334–350. Dutton, Tom E. 1996. Koiari (Languages of the World/Materials, 10). München: Lincom Europa. Easterday, Shelece. 2017. Highly complex syllable structure: A typological study of its phonological characteristics and diachronic development. Albuquerque: University of New Mexico dissertation. Everett, Daniel L. & Barbara Kern. 1997. Wari’: The Pacaas Novos language of Western Brazil. (Descriptive Grammars Series). London & New York: Routledge. Faust, Norma & Evelyn G. Pike. 1959. The Cocama sound system = o sistema fonemico do kokama (Série lingüística especial no. 1), 10–55. Rio de Janeiro: Publicaciones de Museu Nacional. Ferguson, Charles A. 1966. Assumptions about nasals: A sample study in phonological universals. In Joseph H. Greenberg (ed.), Universals of language,53–60. Cambridge, MA: MIT Press. Field, Kenneth L. 1997. A grammatical overview of Santa Mongolian. Santa Barbara: University of California dissertation. Foley, James. 1977. Foundations of theoretical phonology. Cambridge: Cambridge University Press. Geumann, Anja, Christian Kroos & Hans G. Tillmann. 1999. Are there compensatory effects in natural speech? Proceedings of the 14th International Congress of Phonetic Sciences.399–402. Gordon, Matthew K. 2016. Phonological typology. Oxford: Oxford University Press. Consonant strengthening 299

Greenberg, Joseph. 1969. Some methods of dynamic comparison in linguistics. In Jaan Puhvel (ed.), Substance and structure of language, 147–203. Berkeley and Los Angeles: University of California Press. Greenberg, Joseph. 1978. How does a language acquire gender markers? In Joseph H. Greenberg, Charles A. Ferguson & Edith A. Moravcsik (eds.), Universals of human language, vol. 3: Word structure,47–82. Stanford: Stanford University Press. Guion, Susan Guignard. 1998. The role of perception in the sound change of velar palatalization. Phonetica 55. 18–52. Guirardello, Raquel. 1999. A reference grammar of Trumai. Houston: Rice University dissertation. Hahn, Reinhard F. 1991. Spoken Uyghur. Seattle: University of Washington Press. Harris, James W. & Ellen M. Kaisse. 1999. Palatal vowels, glides and obstruents in Argentinian Spanish. Phonology 16. 117–190. Hay, Jennifer & Paul Foulkes. 2016. The evolution of medial /t/ over real and remembered time. Language 92(2). 298–330. Hay, Jennifer, Janet Pierrehumbert, Abby Walker & Patrick LaShell. 2015. Tracking word frequency effects through 130 years of sound change. Cognition 139. 83–91. Heine, Bernd & Tania Kuteva. 2002. World lexicon of grammaticalization. Cambridge: Cambridge University Press. Hellenthal, Anne-Christie. 2010. A grammar of Sheko. Leiden: Leiden University dissertation. Hock, Hans Henrich. 1986. Principle of historical linguistics. Berlin: Mouton de Gruyter. Hockett, C. F. 1942. A system of descriptive phonology. Language 18. 3–21. Hoff, B. J. 1968. The Carib language: Phonology, morphology, texts and word index. Verhandelingen van het Koninklijk Instituut voor Taal-, Land- en Volkenkunde 55. The Hague: M. Nyhoff. Holt, Dennis. 1999. Pech (Paya). München: Lincom Europa. Honeybone, Patrick. 2001. Lenition inhibition in Liverpool English. English Language and Linguistics 5. 213–249. Honeybone, Patrick. 2008. Lenition, weakening and consonantal strength: Tracing concepts through the history of phonology. In Joaquim Brandão de Carvalho, Tobias Scheer & Philippe Ségéral (eds.), Lenition and fortition,9–92. Berlin: Mouton de Gruyter. Hooper, Joan B. 1976. Introduction to natural generative phonology. New York: Academic Press. Huang, Hui-chuan J. 2015. The phonemic status of /z/ in Squliq Atayal revisited. In Yuchau E. Hsiao & Lian-Hee Wee (eds.), Capturing phonological shades within and across languages, 243–265. Newcastle upon Tyne, UK: Cambridge Scholars Publishing. Jakobi, Angelika. 1990. A Fur grammar: Phonology, morphophonology, and morphology. Hamburg: Helmut Buske Verlag. Jakobi, Angelika & Joachim Crass. 2004. Grammaire du beria (langue saharienne) (Nilo- Saharan: Linguistic Analyses and Documentation, 18.). Köln: Rüdiger Köppe. Janssen, Dirk, Balthasar Bickel & Fernando Zúñiga. 2006. Randomization tests in language typology. Linguistic Typology 10. 419–440. Johnston, Raymond Leslie. 1980. Nakanai of New Britain (Pacific Linguistics B 70). Canberra: Australian National University. Kapatsinski, Vsevolod. 2018. Changing minds changing tools: From learning theory to language acquisition to language change. Cambridge, MA: MIT Press. Kim, Juwon. 2011. A grammar of Ewen (Altaic languages series, 6.). Seoul: Seoul National University Press. 300 Joan Bybee and Shelece Easterday

Kirchner, Robert. 1998. An effort-based approach to consonant lenition. Los Angeles: University of California dissertation. Kirchner, Robert. 2004. Consonant lenition. In Bruce Hayes, Robert Kirchner & Donca Steriade (eds.), Phonetically based phonology, 313–345. West Nyack, NY: Cambridge University Press. Kochetov, Alexei. 2016. Palatalization and glide strengthening as competing repair strategies: Evidence from Kirundi. Glossa: A Journal of General Linguistics 1(14). 1–31. Ladefoged, Peter & Ian Maddieson. 1996. The sounds of the world’s languages. Oxford: Blackwell. Lass, Roger. 1984. Phonology: An introduction to basic concepts (Cambridge Textbooks in Linguistics). Cambridge: Cambridge University Press. Lass, Roger & John M. Anderson. 1975. Old English phonology (Cambridge Studies in Linguistics 14). Cambridge: Cambridge University Press. Lavoie, Lisa M. 1996. Consonant strength: Results of a data base development project. Working Papers of the Cornell Phonetics Laboratory 11. 269–316. Lavoie, Lisa M. 2001. Consonant strength: Phonological patterns and phonetic manifestations Outstanding Dissertations in Linguistics. New York: Garland Publishing Co. Lindblom, Björn. 1990. Explaining phonetic variation: A sketch of the H&H theory. In William J. Hardcastle & Alain Marchal (eds.), Speech production and speech modelling, 403–439. Dordrecht: Kluwer Academic Publishers. Lindblom, Björn, Peter MacNeilage & Michael Studdert-Kennedy. 1984. Self-organizing processes and the explanation of phonological universals. In Brian Butterworth, Bernard Comrie & Östen Dahl (eds.), Explanations for Language Universals, 181–203. New York: Mouton. Lorenz, Edward. 1993. The essence of chaos (Jessie and John Danz Lectures). Seattle: University of Washington. Loughnane, Robyn. 2009. A grammar of Oksapmin. Melbourne: University of Melbourne dissertation. Loughnane, Robyn & Sebastian Fedden. 2011. Is Oksapmin Ok? A study of the genetic rela- tionship between Oksapmin and the Ok languages. Australian Journal of Linguistics 31(1). 1–42. Loving, Richard. 1973. An outline of Awa grammatical structures. In Howard P. McKaughan (ed.), The languages of the Eastern family of the East New Guinea Highland stock,65–87. Seattle: University of Washington Press. Maddieson, Ian. 1984. Patterns of sounds. Cambridge: Cambridge University Press. Manning, Margaret & Naomi Saggers. 1977. A tentative phonemic analysis of Ningil. In Richard Loving (ed.), Phonologies of five Papua New Guinea languages (Workpapers in Papua New Guinea languages 19), 49–72. Ukarumpa, Papua New Guinea: Summer Institute of Linguistics. Maslova, Elena. 2000. A dynamic approach to the verification of distributional universals. Linguistic Typology 4. 307–333. Matisoff, James A. 1973. The grammar of Lahu (University of California Publications in Linguistics 75). Berkeley: University of California Press. Mattoso Câmara Jr., Joaquim 1972. The Portuguese language. Chicago: University of Chicago Press. McElhanon, Kenneth A. 1970. Selepet phonology (Pacific Linguistics B 14). Canberra: Australian National University. Consonant strengthening 301

Mielke, Jeff. 2008. The emergence of distinctive features. Oxford: Oxford University Press. Mooshammer, Christine, Philip Hoole & Anja Geumann. 2006. Interarticulator cohesion within coronal consonant production. The Journal of the Acoustical Society of America 120(2). 1028–1039. Mowrey, Richard & William Pagliuca. 1995. The reductive character of articulatory evolution. Rivista Di Linguistica 7(1). 37–124. Ohala, John J. 1981. The listener as a source of sound change. In Carrie S. Masek, Robert A. Hendrick & Mary F. Miller (eds.), Papers from the parasession on language and language behavior, 178–203. Chicago: Chicago Linguistic Society. Ohala, John J. 2003. Phonetics and historical phonology. In Brian D. Joseph & Richard D. Janda (eds.), Handbook of historical linguistics, 669–686. Oxford: Blackwell Publishers. Osumi, Midori. 1995. Tinrin grammar. Honolulu: University of Hawaii Press. Overall, Simon. 2007. A grammar of Aguaruna. Melbourne: La Trobe University dissertation. Padgett, Jaye. 2008. Glides, vowels, and features. Lingua 118. 1937–1955. Pagliuca, William & Richard Mowrey. 1987. Articulatory evolution. In Anna Giacalone Ramat, Onofrio Carruba & Giuliano Bernini (eds.), Papers from the 7th International Conference on Historical Linguistics, 459–472. Amsterdam: John Benjamins. Park, Indrek. 2012. A grammar of Hidatsa. Bloomington: Indiana University dissertation. Perkins, Revere D. 1989. Statistical techniques for determining language sample size. Studies in Language 13(2). 293–315. Perkins, Revere D. 1992. Deixis, grammar and culture. Amsterdam/Philadelphia: John Benjamins. Perrier, Pascal, Yohan Payan, Majid Zandipour & Joseph Perkell. 2003. Influences of tongue biomechanics on speech movements during the production of velar stop consonants: A modeling study. Journal of the Acoustical Society of America 114(3). 1582–1599. Pouplier, Marianne. 2012. The gaits of speech. In Maria-Josep Solé & Daniel Recasens (eds.), The initiation of sound change: Perception, production and social factors, 147–164. Amsterdam/Philadelphia: John Benjamins. Raymond, William D. & Esther L. Brown. 2012. Are effects of word frequency effects of context of use? An analysis of initial fricative reduction in Spanish. In Stefan Th. Gries & Dagmar S. Divjak (eds.), Frequency effects in language. vol 2: Learning and processing,35–52. Berlin: Mouton de Gruyter. Recasens, Daniel. 2002. Weakening and strengthening in Romance revisited. Rivista Di Linguistica 14(2). 327–373. Recasens, Daniel. 2014. Coarticulation and sound change in Romance. Amsterdam/ Philadelphia: John Benjamins. Recasens, Daniel & Aina Espinosa. 2006. Articulatory, positional and contextual characteristics of palatal consonants: Evidence from Majorcan Catalan. Journal of Phonetics 34. 295–318. Recasens, Daniel & Aina Espinosa. 2009. An articulatory investigation of lingual coarticulatory resistance and aggressiveness for consonants and vowels in Catalan. Journal of the Acoustical Society of America 125. 2288–2298. Rice, Keren. 1989. A grammar of Slave. Berlin: Mouton de Gruyter. Rijkhoff, Jan & Dik Bakker. 1998. Language sampling. Linguistic Typology 2. 263–314. Romero-Méndez, Rodrigo. 2009. A reference grammar of Ayutla Mixe (Tukyo’m ayuujk). Buffalo: State University of New York dissertation. Saltarelli, Mario, Miren Azkarate, David Farwell, John Ortiz de Urbina & Lourdes Onederra. 1988. Basque. New York: Croom Helm. 302 Joan Bybee and Shelece Easterday

Sandalo, Filomena. 1997. A grammar of Kadiweu: With special reference to the polysynthesis parameter (MIT Working Papers in Linguistics 11). Cambridge, Massachusetts: Massachusetts Institute of TechnoIogy Press. Sarvasy, Hannah S. 2014. A grammar of Nungon, a Papuan language of Morobe Province, Papua New Guinea. Cairns: James Cook University dissertation. Shipley, William F. 1964. Maidu grammar (University of California Publications in Linguistics 41). Berkeley: University of California Press. Shorto, Harry L. 1960. Word and syllable patterns in Palaung. Bulletin of the School of Oriental and African Studies 23. 544–557. Sosnik, Ronen, Björn Hauptmann, Avi Karni & Tamar Flash. 2004. When practice leads to coarticulation: The evolution of geometrically defined movement primitives. Experimental Brain Research 156. 422–438. Stenzel, Kristine S. 2004. A reference grammar of Wanano. Boulder: University of Colorado dissertation. Steriade, Donca. 1997. Phonetics in phonology: The case of laryngeal neutralization. Los Angeles: Ms., University of California. Szigetvári, Péter. 2008. What and Where? In Joaquim Brandão de Carvalho, Tobias Scheer & Philippe Ségéral (eds.), Lenition and fortition,93–129. Berlin/New York: Mouton de Gruyter. Taylor, Douglas. 1955. Phonemes of the Hopkins (British Honduras) dialect of Island Carib (=Island Carib I). International Journal of American Linguistics 21. 233–241. Turner, Glen D. 1958. Jivaro: Phonology and morphology. Bloomington: Indiana University dissertation. Vanvik, Arne. 1972. A phonetic-phonemic analysis of Standard Eastern Norwegian. Norwegian Journal of Linguistics 26. 119–164. Vuillermet, Marine. 2012. Grammaire de l’ese ejja, langue tacana d’Amazonie bolivienne. Lyon: Université Lumière Lyon 2 dissertation. Welmers, William Everett. 1946. A descriptive grammar of Fanti (Language 22 (3)supplement). Philadelphia: Linguistic Society of America. (Reprinted in 1966 by the Kraus Reprint Corporation).

Supplementary Material: The online version of this article (https://doi.org/10.1515/lingty- 2019-0015) offers supplementary material containing a list of the languages in the sample, available to authorized users.