THE INDIVIDUAL AND THE ACTUATION OF

Mary Stevens and Jonathan Harrington

Institute for and Speech Processing mes;[email protected]

ABSTRACT las condiciones para el cambio fonético están This paper reviews current experimental siempre presentes. Al mismo tiempo, los approaches to sound change. An ongoing sistemas fonológicos de las lenguas se challenge in sound change research is to link caracterizan por ser considerablemente the initiation of sound change within estables. En este artículo se presentan individual cognitive grammars to the diffusion acercamientos actuales al problema de la of novel variants through the community. The iniciación del cambio fonético. Se mostrará articulatory and perceptual phonetic forces that que los diferentes enfoques acuerdan en la idea bring about the pre-conditions for sound que la variabilidad interindividual puede ser la change and that explain its directionality are clave para comprender cómo de la variación always present in the transmission of spoken sincrónica puede surgir cambio fonético. Se language, yet sound systems are remarkably presentará una visión de conjunto de los stable over time. This paper describes how diferentes factores que dan origen a la recent approaches to the actuation problem variación interindividual, basada en estudios converge on the idea that variability between fonéticos de cuatro áreas: 1) la producción del individuals may be the key to understanding habla, 2) la percepción y el procesamiento how some synchronic variation can become cognitivo, 3) la relación entre la producción y sound change. It then reviews the evidence for la percepción y, 4) la experiencia lingüística y individual differences based on four areas of la imitación. Los resultados de estos estudios phonetic research (speech production, speech señalan que diferencias individuales pueden perception/cognitive processing, the ser el motor del cambio fonético. Al mismo perception-production link, and linguistic tiempo ayudan a explicar por qué el cambio experience and imitation). This evidence fonético es iniciado sólo raras veces – a pesar suggests that differences between individuals de que las interacciones entre hablantes may help to explain why sound change is so generan constantemente las condiciones para rarely actuated even though the phonetic pre- el cambio fonético. conditions are constantly being generated in Palabras clave: cambio fonético, percepción spoken language interactions. del habla, producción del habla, diferencias Keywords: sound change, speech perception, individuales, imitación. speech production, individual differences, 1. INTRODUCTION imitation. The question of how sounds change over time RESUMEN has fascinated speakers and linguists for centuries. Knowledge about sound change El presente artículo reseña actuales enfoques helps to reconstruct our linguistic past and it experimentales del cambio fonético. Un has always been a central part of historical problema recurrente en la investigación del linguistics. But sound change is an especially cambio fonético es vincular la iniciación del popular research topic at present with a cambio fonético en la gramática cognitiva de biannual workshop series established in 2010 un individuo con la cuestión de la difusión de and at least five volumes dedicated to sound nuevas variantes en la comunidad de habla. En change appearing since that time (Recasens, la transmisión del lenguaje oral, las fuerzas Sánchez Miret & Wireback 2010, Solé & articulatorias y perceptivas que hacen surgir Recasens 2012, Sánchez Miret & Recasens 2013, Yu 2013, Harrington & Stevens 2014). given to heterogeneity between individuals in The contributions in these volumes show that approaches to the diffusion of sound change. sound change research now incorporates Labov’s (1963) pioneering research with aspects of many areas of linguistics and residents of Martha’s Vineyard linked speaker neighbouring disciplines including cognitive attitude to participation in a sound change in psychology, computational science, progress and Milroy and Milroy’s (1985) experimental phonetics, laboratory phonology, social network theory suggests certain language acquisition, sociolinguistics, individuals play a more crucial role in phonology and physics. spreading sound change than others depending Sound change can be defined as change to on their social position in the community. An the shared perception and production target for ongoing challenge in sound change research is a speech sound within a speech community, a to link the initiation of sound change within definition that encompasses changes that individual cognitive grammars with the directly impact the number of categorical diffusion of novel variants through the contrasts between sounds (e.g. neutralization) community. as well as changes that involve a shift in the This paper first addresses the way that pronunciation target for a speech sound changes can originate in the everyday without loss or introduction of a phonemic variability of spoken interactions in Section 2. contrast (e.g. vowel chain shifts). The Section 3 then focuses on the actuation of conditions that give rise to sound change are sound change and shows convergence between typically distinguished from those that have to recent approaches on the idea that variability do with its diffusion through a speech between individuals may be the key to community (e.g. Ohala 1993, Joseph & Janda understanding how some synchronic variation 2003). Broadly speaking, phonetic models can become sound change. Expanding on this tend to concentrate on identifying the theme, Section 4 considers the evidence for perceptual and articulatory forces that provide individual differences based on results from the pre-conditions for sound change and that four areas of phonetic research and the drive it in a particular direction (e.g. Ohala potential role of such individual differences in 1993). In order to identify these forces, driving sound change. experimental phonetic studies on sound change often factor out between-participant 2. SYNCHRONIC VARIATION AND variability. On the other hand, individual THE ORIGINS OF SOUND CHANGE speaker-listeners are crucial to the origins of Variability is an inherent part of the sound change because, for sound change to transmission of language between speakers occur, it is individual production and and listeners, and can occur due to a range of perception targets for speech sounds that must linguistic and non-linguistic factors. To change. Or, as Milroy and Milroy (1985:347) illustrate with just one example, local speakers noted “linguistic change must presumably of an Australian English variety typically originate in speakers rather than in languages”. pronounce Melbourne as something like Recent phonetic studies have shown that [ˈmæəbm̩], with a vocalized or completely people with similar linguistic backgrounds can elided /l/ alongside reduction of the second differ in terms of their cognitive mapping unstressed syllable (see e.g. Cox and between the auditory signal and perceptual Palethorpe 2007 on Australian English). categories (Beddor 2009, 2012) and in their Although deviating from the spelling and production of speech sounds (Johnson 2006, causing some comment among visitors, this Koenig et al. 2008). This article explores the pronunciation is not unusual in terms of idea that systematic differences between typical patterns of synchronic variation. /l/ is individual members of a speech community more prone to vocalization in syllable-coda may play an important role in the early stages position than elsewhere (e.g. Recasens 2012) of sound change. Key importance has been and segments in unstressed syllables are more likely to be reduced due to gestural overlap is being said and actively choose to reproduce and blending (de Jong et al. 1993). Frequency that variant in their own speech. of use also influences pronunciation (e.g. Building on a long tradition of linking Bybee 2002), so that one might expect sound change to listener perception (e.g. Paul reduction processes to affect the local 1888 [1886], Baudouin de Courtenay 1972 pronunciation of Melbourne but not e.g. [1895]), Ohala’s model was the first to provide (peach) melba, a phonologically similar but a framework to test the evident parallels comparatively rare item for this particular between synchronic variation and diachronic speech community. The link with historical change in the laboratory. In speech perception, sound change is that synchronic tendencies in listeners normally compensate for the the way speech is produced and perceived can, contextual effects on segments due to over time, cause permanent categorical change coarticulation (e.g. Fowler 2005). For example (e.g. Beckman et al 1992, Hura et al. 1992, listeners typically take account of context Hansson 2008, Harrington 2012). This can be effects such as the more fronted tongue seen by comparing the pronunciation of position in loot than in loop in mapping the Melbourne with English words like salmon auditory signal to their cognitive and talk, for example, in which /l/ is no longer representation for /u/. Ohala (1981) suggests pronounced, or by comparing standard Italian that on some rare occasions the listener may be words (e.g. caldo ‘hot’) with cognates from unable for whatever reason to attribute the other varieties also descended from Latin in contextual variation (in this case /u/-) which /l/ has been modified or lost e.g. caudo, to its source (the /t/ in loot). Here the listener cardo, cada (examples from Rohlfs 1966:342). would interpret the high F2 as an inherent part The similar way that pre-consonantal /l/ is of the vowel /u/, would update their cognitive subject to change in unrelated languages may model with this new ‘hypo-corrected’ variant have its origin in phonetic bias factors that are accordingly (which may then also be common to spoken languages. These biases introduced into the listener’s speech mean that the phonetic variation that provides production). Ohala argues that mini-sound the input to historical sound change is both changes of this kind within an individual’s non-random and directional (Garrett and grammar happen randomly and frequently Johnson 2013). In a recent detailed overview, (2012:23 note 2), and that only a sub-set of Garrett & Johnson (2013) group these bias these may eventually proceed to become a factors into four main areas: motor planning, sound change at the community level. Sound aerodynamic constraints, gestural mechanics, change is rare; this is because, Ohala argues, and perceptual parsing. listeners are normally very good at adjusting Not all instances of synchronic phonetic for contextual variation.1 variation lead to permanent sound change, of Sound changes like /u/-fronting that involve course. Instead, sound change can be seen as a the uncoupling of coarticulatory variation from two-step process of variation and selection its source are most apparent in the case where (Ohala 1981, 1993; Lindblom et al. 1995) or, the source of the coarticulatory effect is similarly, of channel and analytic biases (e.g. eventually lost. A familiar example is Moreton 2008). For Ohala, novel variants arise historical vowel in French (e.g. constantly in production, and their eventual Italian pane v. French pain), a sound change selection for sound change depends entirely on that has been extensively studied by Beddor listener perception. Lindblom et al. (1995) (2009, 2012). Beddor’s experiments suggest instead argue that language users - as listeners and speakers - evaluate novel forms according 1 Ohala (1993) nominates children and L2 learners as to articulatory as well as perceptual and other being more likely to make perceptual errors and, by extension, to drive sound change. It is unlikely that criteria and that selection happens when novel variants arising in this way could lead to sound listeners pay close attention to how something change at the community level because native listeners would identify them as errors and correct them accordingly. that the phonologization (Hyman 1976, 2013) his model. Indeed, bridging the gap between of vowel nasalization comes about via a stage models of grammatical change at the level of where coarticulatory information for the individual listener/speaker and change at nasalization on the vowel gradually becomes a the community level is difficult. 1 The sufficient cue for listeners, while the articulatory and perceptual phonetic forces that information provided by the source (the nasal bring about the pre-conditions for sound consonant) becomes less important and may change and that explain its directionality are eventually be lost. Alternatively, Kirby (2013) always present in the transmission of spoken describes how the waning of one cue can drive language, yet sound systems are remarkably the enhancement and phonologization of stable over time. How is it that sound change another. Kirby models this relationship with an does not always happen whenever the agent-based simulation of a sound change necessary pre-conditions are met? What causes underway in Seoul Korean involving the sound change actuation? phonologization of F0 and dephonologization of voicing. 3. THE ACTUATION PROBLEM Key to Ohala’s model is the idea that many The link between innovation within an sound changes have a perceptual origin individual’s grammar, on the one hand, and without involving a change to speech widespread change for most members of a production. However as Beddor (2012:51) speech community on the other, is sound points out “perceptual grammars only change actuation. There is no clear consensus contribute to sound change […] if they are in the sound change literature on the precise publicly manifested”. Browman & Goldstein meaning of the term actuation and how it (1991) suggested that interactions between should be distinguished from initiation and perception and production over time at the spread. Ohala draws a distinction between the level of the individual language user cause the initiation of sound change versus its shared target for a speech sound to move in a actuation/spread, whereas in Yu’s account particular direction. The idea that sound (2013:201) sound change actuation is seen as change, at its origins, involves articulatory comprising variation and selection (i.e. as factors in combination with perceptual comprising initiation). The terms initiation and considerations is supported by the results of a actuation are used synonymously in some recent physiological study on /l/-vocalization sources, for example Hansson (2008:8) who in American English. Lin et al. (2014) find that refers to the “initiation (actuation) phase of a small degree of articulatory reduction in the sound change”, whereas the terms actuation apical gesture for /l/ in words like milk and and spread are used synonymously in others. help (measured as tongue tip aperture on Baker et al. (2011:348), for example, suggest ultrasound displays) can have major acoustic that a sound change is actuated when an consequences, causing the first two formants individual (listener) reproduces a perceived to merge. Lin et al. point out that this small novel variant in their own speech; they claim articulatory shift in tongue aperture could at this point “the sound change has begun to make a quantal difference in perception and propagate around the community”. Hansson raise the idea that this might be a driving and Baker et al. agree, then, that a sound factor in causing /l/-vocalization. In other words some articulatory changes may only be 1 Bybee (2012:221) suggests “a change does not have to slight on the part of the speaker, but start with […] just one person”. Bybee argues that nonetheless enough to cause the listener to articulation, not perception, drives sound change and reinterpret the sound category a la Ohala’s that all members of a speech community are biased model. towards the same kinds of articulatory reductions and casual speech processes. At this general level one could Ohala (2012: note 2) explicitly also argue that all listeners would make the same distinguishes initiation from actuation and perceptual ‘error’. In any case, articulatory ease cannot chooses to account only for the former within account for all kinds of sound changes (cf. e.g. Hansson 2008 on this point). change is not only initiated but also actuated in intervening /t/) can be considered to be the mind of the individual listener. Elsewhere generally present amongst English speakers. in the literature this stage of listener-turned- Given that /s/-retraction has been speaker production is not considered to be phonologized in some (e.g. New Zealand sound change but rather to be an innovative English) but not all varieties, the difficulty, as “act of an individual speaker, regardless of Baker et al. (2011:350) point out “lies in whether or not it later catches on in a speech creating a theory in which sound change can community” (Joseph and Janda 2003:17-18). plausibly occur, but without making sound Joseph and Janda argue that sound change change inevitable”. Baker et al. (2011) propose should be “strictly defined as an innovation that variability becomes sound change, i.e. a that has been widely adopted by members of sound change is actuated, because individuals […] a community” (cf. also Milroy and Milroy differ in the degree to which they coarticulate 1985). (retract). Speakers who do not tend to retract Weinreich et al. (1968) famously identified /s/ will interpret [ʃ]-like productions as a the actuation problem by asking “what factors distinct target, and might imitate them can account for the actuation of changes? Why accordingly. Crucial to this model is the idea do changes in a structural feature take place in that coarticulatory effects must be sufficiently a particular language at a given time, but not in perceptible if they are to be imitated by other other languages with the same feature, or in members of the speech community (i.e. the same language at other times?” For these ambiguous tokens would be unlikely to be authors and others since (e.g. Campbell imitated because “if every speaker has 2013:193), actuation is key to explaining essentially the same amount of coarticulation, linguistic change because it relates to all other then there is nothing to imitate in the first sociolinguistic and structural factors. Ohala place” (2011:350)). This model of Baker et al. (2002: note 2) is instead of the view that also generally predicts that coarticulatory attempting to explain actuation, i.e. whether, effects that vary across speakers would be where or when change may actually happen more likely to undergo sound change than can be likened to “asking why a coin flip those common to all speakers within a speech results in ‘heads’ and not ‘tails’”. community. Baker et al. present only At least three recent studies have production data but it would be possible to test nevertheless addressed the actuation explicitly, these predictions about the role of inter- namely Baker et al. (2011), Garrett and speaker differences in sound change actuation Johnson (2013) and Yu (2013). Baker et al. with standard shadowing experiments. For (2011) propose that actuation comes about via example, one could recruit a group of speakers interactions between individuals whose targets from a variety of English without /s/- for a speech sound fall at opposite ends of a retraction. Following Baker et al. these production continuum, taking as a case study speakers could be classified as /s/-retraction in American English. Baker et al. “retractors”/”non-retractors” based on the classified speakers as “retractors” and “non- proportion of str- productions judged to be [ʃ] retractors” according to the proportion of their or [s]. After exposure to words containing tokens that were judged (by the authors) to be extreme [ʃ]-like tokens, only those speakers retracted or not (62.50% and 35.48%, whose own productions typically fall at the respectively). Baker et al. show that even [s]-end of the continuum should show a speakers classified as “non-retractors” (i.e. change in the direction of [ʃ], whereas those who pronounce e.g. stream more like individuals with ambiguous productions [stɹ] than [ʃtɹ]) show a lower centroid between [ʃ] and [s] should not shift their frequency for /s/ in clusters, and especially so production target. for clusters containing /r/. As such they argue Garrett and Johnson (2013) propose that that the phonetic motivation for /s/-retraction some individuals are more likely to attach ( to retroflex /r/ across the social meaning to linguistic differences than others and that this is a driving force in the represent individuals with more sensitivity to actuation of sound change. They draw on social differences. After more than fifty experimental work by Dimov (2010; also iterations the two groups’ productions Dimov et al. 2012) that found a link between diverged according to how they responded to social and personality traits and the extent to the novel variants; the group that did not which participants compensated for altered compensate for the articulatory bias came to auditory feedback (for /u/). Dimov and produce /r/-like tokens in their own output. In colleagues’ experimental work showed that the this way Garrett and Johnson model the update more powerful subjects judged themselves to of novel variants according to whether or not be, based on responses to survey they are cognitively stored in individuals. questionnaires, the less they compensated in Yu (2013) addresses the role of individual the experimental task (i.e. they were either less cognitive processing style in the actuation of finely attuned to phonetic variation or less sound change. He compares the categorization willing to modify their own production in of CV stimuli (where C is an /s…ʃ/ continuum order to compensate for it). Garrett and and V = /i, u/) with personality and social traits Johnson (2013) build on this experimental as measured by a number of standard research together with Giles et al.’s (1991) questionnaires. Yu reports that neurotypical work on accommodation to suggest that listeners with fewer autistic traits (more individuals who wish to identify with a group specifically a lower Autism Quotient (AQ)) may be more likely to interpret intrinsic are less likely to link coarticulatory phonetic variability (primarily due to information during the fricative to its source in coarticulation) as indexing group membership. the following /u/ (i.e. more “ʃu” responses) As a result they would attach a social than listeners with a high AQ who tend to significance to phonetic properties that compensate for context (and give more “su” previously had none. An exemplar-based responses accordingly). Yu argues that by model predicts that if listeners attach social failing to compensate for coarticulation, meaning to coarticulatory information then participants with a low AQ may be responsible they will store both components i.e. the for the creation of novel variants. Yu then coarticulatory information together with the relates AQ (and its sub-components of social meaning that it is assumed to convey. attention and social skills) to a number of On the other hand, listeners who compensate personality and social traits. Ultimately Yu for coarticulation would discard this suggests that the same individuals who are contextual information before storing the likely to undergo mini-sound changes might exemplar in their cognitive grammar. This also be more likely, due to their (more model therefore predicts that individuals who extroverted and agreeable) personality and attach social significance to coarticulatory social profiles, to spread such innovations information are more likely to participate in within their social networks. sound change than those individuals who do These three approaches together suggest not, and whose exemplar clouds (and that the selection of sound changes from a pool pronunciations) should remain stable over of synchronic variation depends on differences time. Garrett and Johnson (2013) simulate between individual members that make up a their model with two groups of autonomous speech community. These differences are not agents who were exposed to phonetic tokens due to chance but rather involve factors that for /z/ whose variants included a small number are identifiable and generalizable to other that were affected by an articulatory bias so groups of language users. For Baker et al. the that they sounded more like an approximant systematic difference lies in production, /r/. One group was modelled to compensate for whereas for Garrett and Johnson it involves the articulatory bias, essentially discarding the sensitivity to social factors and for Yu it novel approximant variants, whereas the other involves cognitive and social traits. Common group did not, and was thus intended to to Garrett and Johnson (2013) and Yu (2013) is the way that individual listener individuals for its own sake. He points out that interpretation provides the catalyst for sound “some further justification for the description change and speaker productions do not change of variation is required; otherwise there will be - at least initially. Differences across no stop to the enterprise and we will be individual speaker productions are instead plunged into an endless pursuit of detail”. crucial to Baker et al.’s (2011) model, and can Labov goes on to point out that variation is only subsequently be perceived and possibly crucial to language change, in particular, and imitated by listeners. This echoes Lindblom et indeed the further justification here is that we al. (1995:16) who also suggested that there do not yet have a model of how sound change must be “significant change in the phonetic is actuated. That is, we need to link the pattern” for a variant to be noticed by listeners initiation of sound change in an individual’s and to eventually undergo sound change. cognitive grammar and widespread change at The role of phonetic similarity in driving the group level. The approaches outlined sound change actuation deserves further above suggest that actuation is dependent on experimental investigation. In contrast with variation between individuals that make up Baker et al., Garrett and Johnson hypothesize speech communities. An ongoing challenge is that slight phonetic differences in production to identify the factors responsible for may be more likely to lead to sound change variability within groups of individuals who than larger differences, because they would interact on a daily basis. not be detected by listeners and would therefore be included amongst stored 4.1. Speech production differences exemplars. Garrett and Johnson hypothesize Speech production is idiosyncratic and that more dramatic phonetic differences due to differences between speakers can be attributed e.g. production errors (here one could also to learned behaviour as well as to physiology consider Baker et al.’s exaggerated (Ladefoged and Broadbent 1957, Johnson et coarticulations) would not be automatically al. 1993, Koenig et al. 2008). There are reports stored in a listener’s representation and would in the phonetic literature of speaker-specific need to take on a socio-indexical meaning to strategies for achieving articulatory goals for participate in sound change. Evidence from the stable phonemic categories (Koenig et al. 2008 imitation literature (described in more detail on fricatives and Beddor 2009 on nasals, both below) favours the idea that phonetically for American English). Synchronic is similar variants would be more likely to also reported to be speaker-specific. For undergo sound change. For example in example lenition of /p t k/ in Florentine and spontaneous conversations, Kim et al. (2011) other varieties of Italian spoken in Tuscany is report more imitation between speaker pairs most prominent for velar /k/, which is typically who both shared the same dialect background reduced to /h/ and can be elided altogether. than between pairs with different linguistic Yet there is evidence (e.g. Dalcher 2008) that backgrounds. Olmstead et al. (2013) report certain speakers resist /k/-reduction. Dalcher that native Spanish and English listeners’ (2008) attributes this variability to external imitation of an 11-step [ba]–[pa] continuum social factors, in this case to the extent to showed less convergence outside the bounds which individual speakers identified positively of their native pronunciation range (i.e. with being “Florentine” and therefore chose to English listeners converged less in the lenite /k/ (echoing Labov’s 1963 seminal study prevoiced region and Spanish listeners of speaker attitude and vowel centralization in converged less for the long lag region). Martha’s vineyard). In contrast to the Gorgia toscana which is a stereotypical feature of

4. SYSTEMATIC INDIVIDUAL Tuscan speech (e.g. Giannelli 1997, Bertinetto DIFFERENCES AND SOUND CHANGE & Loporcaro 2005), lenition of /b d g/ in Labov (2006:508) has argued that we should contemporary spoken Danish does not appear not seek to code linguistic variation between to carry any social meaning but does nonetheless also show speaker-specific "there is no reason to expect psychophysical patterns in terms of thresholds for simple or complex stimuli to (Pharao 2011). Pharao analysed group-level vary from language to language". However, patterns of reduction of /b d g/ using mixed since there is evidence that people with similar effect models with individual speaker as a linguistic backgrounds can differ in the way random factor, the results of which suggest that they hear and process auditory signals reduction of /b/ and /g/ (but not /d/) belong to (including relatively simple tones as well as the same target undershoot process. However speech sounds) it is conceivable that such six of the 22 speaker participants did not differences could play a role in sound change. conform to the group-level pattern, and instead Beddor (2012), for example, suggests that showed divergent tendencies for reduction of sound change can arise out of the idiosyncratic /b/ and /d/. Both of these studies illustrate that way in which coarticulation is perceived. lenition processes are not automatic, because Along the lines of Milroy and Milroy’s (1985) otherwise individual speakers would show notion of an innovative speaker, Beddor similar place-governed patterns. (2012:51) describes the innovative listener as Solé (2014) makes an explicit link between one who comes to map the auditory input to fine-grained inter-speaker differences in abstract categories in a novel way that, if this production and the origins of sound change. is matched in production, could drive sound Using oral and glottal airflow measurements, change. Solé shows that some Spanish speakers show There is an auditory illusion whereby nasal airflow leakage in the production of human listeners normally hear a that is voiced stops /b d g/, which serves to enhance interrupted by a noise-filled gap as continuous, the voiced status of /b d g/ by reducing despite the intervening noise. This auditory supraglottal pressure and facilitating vocal fold illusion is due to perceptual restoration, an vibration. Solé describes nasal airflow leakage adaptive skill developed in late childhood in this context as an implementational feature (Warren & Warren 1971) and crucial to and argues that such features can be processing auditory information - including distinguished from other kinds of phonetic speech - in noisy environments. Yet recent variation because they are planned (rather than evidence shows that individuals vary in the mechanical) on the part of the speaker who extent to which they experience this illusion: intends to produce a specific acoustic effect Vinnik et al. (2011) found that nearly one and because only some speakers use them in quarter of their 46 participants reported some contexts (i.e. they are not fully hearing an interrupted tone signal as predictable). Notably, Solé’s perceptual discontinuous. This result shows that even for analysis shows that listeners have difficulty relatively simple auditory tasks listeners differ parsing nasal airflow leakage with the source, in the extent to which they weight the auditory and can interpret it as a separate nasal signal against information from top-down segment. Solé proposes that low-level perceptual restoration processes. implementational features are more likely to Speech perception is affected by a listener’s undergo sound change not only because they native phonological system, which influences are difficult for listeners to parse but precisely their ability to detect speech sounds (Mielke because they vary across speakers. 2003) and to categorize them (e.g. Bohn et al. 2011, Davidson 2011). However, even within 4.2. Perception and cognitive processing groups of people with similar language style backgrounds, speech perception can differ Functional and anatomical differences between from person to person. Beddor’s (2009, 2012) human listeners’ peripheral auditory systems well-known research reported idiosyncratic are not normally considered to affect the long- behaviour in the perception of nasalization in term stability of shared sound systems. VNC sequences in American English, whereby Johnson (2004:26), for example, points out listeners differed in their sensitivity to and weighting of fine phonetic detail. Beddor parsing strategies that would serve to weaken suggests that listeners who compensate less for phonological category boundaries over time. coarticulation could be more likely to initiate sound change (we saw earlier that Yu relates 4.3. The perception-production link compensation for coarticulation to a person’s Ohala’s model of sound change initiation (and Autistic Quotient). that of e.g. Baker et al. 2011) is implicitly Some recent research in our lab has also founded on a direct relationship between looked at individual differences in perception perception and production in the sense that and the extent to which such differences might listeners turned speakers would reproduce initiate sound change. Following reports that novel perceptual targets in their own geminate /p: t: k:/ can be optionally produced subsequent productions. However the with pre-aspiration in contemporary spoken experimental evidence of a direct link between Italian (e.g. Stevens 2012) Stevens & Reubold perception and production at the level of the (submitted) investigated the impact of pre- individual language user is mixed. Beddor aspiration on native listener perception of (2009) compared results for one participant phonemic consonant length. Two continua across perception and production tasks and were synthesized, one from short fato ‘fate’ to found that they were aligned: the long fatto ‘done’ and the other in which a presence/absence of a nasal consonant was portion of the closure duration for the dental poorly discriminated in perception (in e.g. bed stop was replaced by pre-aspiration. The v. bent), and this participant also showed results of a forced-choice perception relatively more variability in production. In a experiment (n participants =16) showed larger-scale comparison involving nineteen significantly more fato responses for the pre- participants, Perkell et al. (2004) report that an aspirated continuum. Most listeners conformed individual’s ability to discriminate vowel to this group-level pattern but two showed no phoneme pairs (e.g. who’d v. hood) in difference between the pre-aspirated and plain perception could predict the acoustic continua. In other words, these two separation of these same vowels in production. participants parsed pre-aspiration with the There is also evidence of a close parallel consonant (= /t:/), whereas all other listeners between perception and production for sub- parsed it with the vowel (= /t/). Since there are groups of listeners who differ in their two different parsing strategies for pre- linguistic experience due to age (Harrington et aspiration, then the type of resulting listener- al. 2008) and socio-economic background driven sound change cannot be predicted (Hay et al. 2006). On the other hand Kataoka (whereas perceptual confusion is typically (2011) reports that for /u/-fronting in asymmetrical, e.g. Garrett & Johnson 2013). American English the extent to which a Notably however, the two different parsing participant compensated for coarticulation in strategies correspond to dialect differences for perception was not correlated with the degree pre-aspiration in Swedish (Wretling et al. of coarticulation in that same subject’s 2003), suggesting that sound changes productions. Stevens and Reubold (submitted) involving pre-aspiration might be directly also compared the perception of pre-aspiration influenced by individual perceptual patterns. (described above) with the production of Ohala’s listener-driven model of sound change geminate /t:/ within each participant. Six has been criticised on the assumption that all subjects parsed pre-aspiration with the listeners must eventually make the same preceding vowel in perception and in perceptual error (Baker et al. 2011, Bybee production, but seven subjects showed a 2012). However, perhaps it is not necessary to mismatch across the two experimental tasks assume that all listeners make the same error. (e.g. assigning pre-aspiration to the preceding Rather, sound change could be driven by vowel /at/ in production but to the consonant interactions between listeners with different /at:/ in perception). This shows that sound change could originate not only form idiosyncratic perceptual parsing strategies (in 4.4. Linguistic experience over a lifetime line with Beddor 2009, 2012) but also because and imitation not all subjects align their perception and Linguistic experience accumulated over an production of coarticulation in the same way. individual’s lifetime is another potential Based on data from 28 participants, Grosvald source of sound change. A person’s speech can & Corina (2012) also found that the perception change to reflect ongoing change taking place and production of long-distance vowel in the wider community, not just during the coarticulation were not correlated at the level earliest phases of language acquisition but of the individual. Grosvald and Corina’s data over the lifespan (Harrington 2007, Sankoff & showed that subjects who were especially Blondeau 2007). Sankoff and Blondeau sensitive to long-distance coarticulatory effects (2007:584) examined /r/ production in on schwa in perception did not tend to produce Montreal French over a thirteen year period more coarticulation in their own speech. This and showed that a minority of speakers experimental result (together with those of changed their production. Some altered only Kataoka 2011 and Stevens and Reubold, the frequency of the two (apical or dorsal) submitted) appears to cast some doubt on variants but others replaced the apical variant models of sound change that assume that an “that they appeared to use spontaneously and individual listener would match novel unreflectingly with the innovative [… dorsal perceptual categories in their own productions variant] characteristic of speakers younger (e.g. Ohala 1993, Baker et al. 2011). Here than themselves”. Such change over the Grosvald & Corina (2012:96) suggest a more lifespan is understood to come about because nuanced interpretation whereby “it does not cognitive models are the result of statistical matter if the speech community at large generalizations over linguistic experiences and exhibits a perception-production correlation or are constantly being updated (e.g. not” but rather that some small proportion of Pierrehumbert 2003). Because no two people the community does. According to these can take part in exactly the same conversations authors, it is only this small proportion of the and have exactly the same linguistic community that would be (a) especially experiences, everyone’s cognitive model must sensitive to novel variants in perception and be uniquely different. The effect of linguistic (b) likely to match or exaggerate these variants experience can be seen in speech processing, in production (Grosvald and Corina point out for example, which is affected by familiarity that for their experimental data, only one with different dialects (Clopper 2014). subject appears to fall into this category). The Moreover social knowledge and expectations notion that the strength of the link between about a speaker’s social attributes affect the perception and production might vary between perceptual categorization of speech sounds individuals and that very few individuals (Hay, Warren and Drager 2006). Non- would meet both criterion (a) and criterion (b) linguistic experiences such musical training is tantalizing because, taken together with the can also affect the perception and production idea of sound change as a process of variation of linguistic contrasts (cf. e.g. Yu 2013:204 and selection, it implies that only a small and references therein). portion of the speech community would be While individuals can update their sound able to select sound changes from the pool of categories, longitudinal studies (Sankoff & synchronic variation. This would help to Blondeau 2007, Kammacher et al. 2011) show explain why sound change is so rarely actuated that not all individuals participate in the sound even though the phonetic pre-conditions for changes taking place around them. This brings sound change are constantly being generated us to imitation (or accommodation), which in spoken language interactions. refers to the way that an individual’s speech can come to resemble that of their interlocutor. Imitation has been documented in experimental tasks involving modified single word tokens (Nielsen 2011) and between as judged globally by naive listeners in an individuals who interacted over longer time AXB task, but individuals varied in the degree periods (Pardo et al. 2012). Imitation is to which they did so. Indeed Pardo et al. understood to be one of the factors by which a (2012:196) emphasize the complexity of sound change can spread through a imitation and raise the idea that “each community; it is also thought to play a role in individual talker might converge on a unique first language acquisition and dialect set of acoustic-phonetic attributes while convergence (Trudgill 1986). diverging, varying randomly, or remaining Empirical studies show that imitation is not neutral on others”. automatic but rather that it is constrained by linguistic factors (e.g. Nielsen 2011) as well as 5. FINAL COMMENTS social preferences (Babel 2012) including self- While phonetic research on the origins of reported closeness to the interlocutor (Pardo et sound change has tended to focus on group- al. 2012) and novelty of the interlocutor’s level biases in speech production and voice (Babel et al. 2014 for gender-atypical perception, it appears that sound change voices). Yu et al. (2013) report variability should be seen as the result of interactions between subjects in the extent of imitation between individuals who have slightly after exposure to a narrative containing different cognitive mappings, perceptual extended VOT durations. Measured in terms abilities, production strategies or sensitivities of acoustic VOT, some individuals converged to particular social factors. Identifying these towards while others diverged from the factors and the range of variability between narrator in ways that were found to depend on individuals who make up a speech community attitude and social/personality factors. Overall is vital to understanding what causes certain however, Yu et al. found no effect of imitation sound categories, but not others, to become at the group level. Nielsen (2011) on the other unstable over time. hand, did report an overall effect of imitation after exposure to increased VOT in isolated 6. ACKNOWLEDGMENTS words. Yu et al. (2013:11) note that “imitation This research was supported by the European might be more automatic […] in a context Research Council Advanced Grant no 295573 where the words are presented in isolation ‘Sound change and the acquisition of speech’ devoid of social significance” whereas their (2012-2017) to Jonathan Harrington. We are study allowed participants to make evaluative very grateful to Hanna Ruch for translating our judgements about the speaker during a abstract into Spanish at short notice. narrative. This observation is reminiscent of Lindblom et al.’s (1995) notion of bimodal listener perception, noted in §2 earlier, and the 7. REFERENCES suggestion that the ‘how’ mode of listening Babel, M., McGuire, G., Walters, S., & (and not the ‘what’ mode) would feed sound Nicholls, A. (2014). Novelty and social change. The fact that imitation is more typical preference in phonetic accommodation. in tasks involving single word items than after Laboratory Phonology, 5(1), 123-150. exposure to narratives supports Lindblom et Baker, A., Archangeli, D., & Mielke, J. al.’s notion that imitation, and by extension (2011). Variability in American English s- sound change, might happen when listeners retraction suggests a solution to the actuation pay particular attention to how something is problem. Language variation and change, 23, being said. Pardo et al.’s (2012) study 347-374. involving college roommates shows that Baudouin de Courtenay, J. (1972 [1895]). imitation also happens in more natural settings An attempt at a theory of phonetic alternations. (and indeed it must, to play a role in sound In E. Stankiewicz (Ed.), A Baudouin de change). All five participant-pairs in Pardo et Courtenay anthology: the beginnings of al.’s study converged over an academic year, structural linguistics (pp. 144-212). dialect speech processing. Laboratory Bloomington: Indiana University Press. Phonology, 5(1), 69-90. Beckman, M., De Jong, K., Jun, S.-A., & Cox, F., & Palethorpe, S. (2007). Australian Lee, S.-H. (1992). The interaction of English. Journal of the International Phonetic coarticulation and prosody in sound change. Association, 37(3), 341-350. Language and Speech, 35, 45–58. Dalcher, C. V. (2008). Consonant Beddor, P. S. (2009). A coarticulatory path weakening in Florentine Italian: a cross- to sound change. Language, 85(4), 407-428. disciplinary approach to gradient and variable Beddor, P. S. (2012). Perception grammars sound change. Language variation and change, and sound change. In M.-J. Solé & D. 20, 275-316. Recasens (Eds.), The initiation of sound Davidson, L. (2011). Phonetic, phonemic, change: perception, production, and social and phonological factors in cross-language factors (pp. 37-55). Amsterdam/Philadelphia: discrimination of phonotactic contrasts. John Benjamins. Journal of Experimental Psychology: Human Bertinetto, P. M., & Loporcaro, M. (2005). Perception and Performance 37(1), 270-282. The sound pattern of Standard Italian, as de Jong, K., Beckman, M. E., & Edwards, compared with the varieties spoken in J. (1993). The interplay between prosodic Florence, Milan and Rome. Journal of the structure and coarticulation. Language and International Phonetic Association, 35(2), 131- Speech, 36(2-3), 197-212. 151. Dimov, S. (2010). Social and Personality Bohn, O.-S., Best, C. T., Avesani, C., & Variables in Compensation for Altered Vayra, M. (2011). Perceiving through the lens Auditory Feedback. UC Berkeley Phonology of native phonetics: Italian and Danish Lab Annual Report, 259–282. listeners' perception of English consonant Dimov, S., Katseff, S. & Johnson, K. contrasts. Proc. ICPhS XVII. Hong Kong: (2012). Social and Personality Variables in 336-339. Compensation for Altered Auditory Feedback. Browman, C., & Goldstein, L. (1991). In M.-J. Solé & D. Recasens (Eds.), The Gestural structures: distinctiveness, initiation of sound change: Perception, phonological processes, and historical change. production, and social factors (pp. 185-210). In I. G. Mattingly & M. Studdert-Kennedy Amsterdam & Philadelphia: John Benjamins. (Eds.), Modularity and the motor theory of Fowler, C. A. (2005). Parsing coarticulated speech perception: Proceedings of a speech in perception. Journal of Phonetics, 33, conference to honor Alvin M. Liberman (pp. 199-213. 313-338). New Jersey: Lawrence Erlbaum Garrett, A., & Johnson, K. (2013). Phonetic Associates, Inc. bias in sound change. In A. Yu (Ed.), Origins Bybee, J. (2002). Word frequency and of sound change: Approaches to context of use in the lexical diffusion of phonologization (pp. 51-97). Oxford: Oxford phonetically conditioned sound change. University Press. Language variation and change, 14, 261–290. Giannelli, L. (1997). Tuscany. In M. Bybee, J. (2012). Patterns of lexical Maiden & M. Parry (Eds.), The Dialects of diffusion and articulatory motivation for sound Italy (pp. 297-302). New York: Routledge. change. In M.-J. Solé & D. Recasens (Eds.), Grosvald, M., & Corina, D. (2012). The The initiation of sound change. Perception, production and perception of sub-phonemic production and social factors (pp. 211-234). vowel contrasts and the role of the listener in Amsterdam/Philadelphia: John Benjamins. sound change. In M.-J. Solé & D. Recasens Campbell, L. (2013). Historical linguistics: (Eds.), The Initiation of Sound Change: an introduction (Third Edition). Edinburgh: Perception, production, and social factors (pp. Edinburgh University Press. 77–100). Amsterdam/Philadelphia: John Clopper, C. G. (2014). Sound change in the Benjamins. individual: Effects of exposure on cross- Hansson, G. Ó. (2008). Diachronic Lexicon. In A. Agwuele, W. Warren & S.-H. explanations of sound patterns. Language & Park (Eds.), Proceedings of the 2003 Texas Linguistics Compass, 2(5), 859-893. Linguistics Society Conference (pp. 26-41). Harrington, J. (2007). Evidence for a Somerville, MA: Cascadilla Proceedings relationship between synchronic variability Project. and diachronic change in the Queen’s annual Johnson, K. (2006). Resonance in an Christmas broadcasts. . In J. Cole & J. Hualde exemplar-based lexicon: The emergence of (Eds.), Laboratory Phonology 9 (pp. 125-143). social identity and phonology. Journal of Berlin: Mouton. Phonetics 34, 485–499. Harrington, J. (2012). The relationship Kammacher, L., Stæhr, A., & Jørgensen, J. between synchronic variation and diachronic N. (2011). Attitudinal and sociostructural change. In A. Cohn, C. Fougeron & M. factors and their role in dialect change: Testing Huffman (Eds.), Handbook of Laboratory a model of subjective factors. Language Phonology (pp. 321 - 332). Oxford: Oxford Variation and Change, 23, 87–104. University Press. Kataoka, R. (2011). Phonetic and Cognitive Harrington, J., Kleber, F., & Reubold, U. Bases of Sound Change. PhD Dissertation. UC (2008). Compensation for coarticulation, /u/- Berkeley. fronting, and sound change in standard Kim, M., Horton, W. S. & Bradlow, A. R. southern British: An acoustic and perceptual (2011). Phonetic convergence in spontaneous study. Journal of the Acoustical Society of conversations as a function of interlocutor America, 123(5), 2825-2835. language distance. Laboratory Phonology 2(1). Harrington, J., & Stevens, M. (2014). 125-156. Editors' introduction: Cognitive processing as Kirby, J. (2013). The role of probabilistic a bridge between phonetic and social models enhancement in phonologization. In In A. C. of sound change. Laboratory Phonology, 5(1), L. Yu (Ed.), Origin of Sound Change: 1-8. Approaches to Phonologization. Oxford: OUP. Hay, J., Warren, P., & Drager, K. (2006). Koenig, L. L., Lucero, J. C., & Perlman, E. Factors influencing speech perception in the (2008). Speech production variability in context of a merger-in-progress. Journal of fricatives of children and adults: Results of Phonetics, 34, 458–484. functional data analysis. Journal of the Hura, S. L., Lindblom, B., & Diehl, R. L. Acoustical Society of America, 124(5), 3158- (1992). On the role of perception in shaping 3170. phonological assimilation rules. Language and Labov, W. (1963). The social motivation of Speech, 35(1,2), 59-72. a sound change. Word, 19, 273-309. Hyman, L. M. (1976). Phonologization. In Labov, W. (2006). A sociolinguistic A. Juilland (Ed.), Linguistic studies presented perspective on sociophonetic research. Journal to Joseph H. Greenberg (pp. 407-418). of Phonetics 34, 500–515. Saratoga: Anma Libri. Ladefoged, P., & Broadbent, D. (1957). Hyman, L. M. (2013). Enlarging the scope Information conveyed by vowels. Journal of of phonologization. In A. C. L. Yu (Ed.), the Acoustical Society of America, 29(1), 98- Origins of Sound Change: Approaches to 104. Phonologization (pp. 3-28). Oxford: Oxford Lin, S., Beddor, P. S., & Coetzee, A. W. University Press. (2014). Gestural reduction, lexical frequency, Janda, R. D., & Joseph, B. D. (2003). On and sound change: a study of post-vocalic /l/. Language, Change and Language Change. In Laboratory Phonology, 5(1), 9-36. R. D. Janda & B. D. Joseph (Eds.), The Lindblom, B., Guion, S., Hura, S., Moon, Handbook of Historical Linguistics (pp. 3- S.-J., & Willerman, R. (1995). Is sound change 180): Wiley-Blackwell. adaptive? Rivista di linguistica, 7(1), 5-37. Johnson, K. (2004). Cross-linguistic Mielke, J. (2003). The interplay of speech Perceptual Differences Emerge from the perception and phonology: experimental evidence from Turkish. Phonetica, 60, 208- Pharao, N. (2011). Plosive reduction at the 229. group level and in the individual speaker. Milroy, J., & Milroy, L. (1985). Linguistic ICPhS XVI, Hong Kong: 1590-1593. change, social network and speaker Pierrehumbert, J. B. (2003). Phonetic innovation. Journal of Linguistics, 21, 339- Diversity, Statistical Learning, and Acquisition 384. of Phonology. Language and Speech, 46(2-3), Moreton, E. (2008). Analytic Bias as a 115-154. Factor in Phonological Typology. In C. B. Recasens, D. (2012). A phonetic Chang & H. J. Haynie (Eds.), Proceedings of interpretation of changes affecting dark /l/ in the 26th West Coast Conference on Formal Romance. In M.-J. Solé & D. Recasens (Eds.), Linguistics (pp. 393-401). Somerville, MA: The Initiation of Sound Change: Perception, Cascadilla Proceedings Project. production, and social factors (pp. 57–76). Nielsen, K. (2011). Specificity and Amsterdam/Philadelphia: John Benjamins. abstractness of VOT imitation. Journal of Recasens, D., Sánchez Miret, F., & Phonetics, 39(2), 132–142. Wireback, K. (2010). Experimental Phonetics Ohala, J. (1993). The phonetics of sound and Sound Change. München: Lincom Europa. change. In C. Jones (Ed.), Historical Rohlfs, G. (1966). Grammatica storica della Linguistics: Problems and Perspectives (pp. lingua italiana e dei suoi dialetti: fonetica (Vol. 237-278). London: Longman. 148). Pisa: Einaudi. Ohala, J. (2012). The listener as a source of Sánchez Miret, F., & Recasens, D. (2013). sound change. An Update. In M.-J. Solé & D. Studies in Phonetics, Phonology and Sound Recasens (Eds.), The initiation of sound Change in Romance. München: Lincom change. Perception, production and social Europa. factors (pp. 21-36). Amsterdam/Philadelphia: Sankoff, G., & Blondeau, H. (2007). John Benjamins. Language change across the lifespan: /r/ in Ohala, J. J. (1981). The listener as a source Montreal French. Language, 83(3), 560-588. of sound change. In C. S. Masek, R. A. Solé, M.-J. (2014). The perception of voice- Hendrick & M. F. Miller (Eds.), Papers from initiating gestures. Laboratory Phonology, the Parasession on Language and Behavior 5(1), 37-69. (pp. 178 - 203). Chicago: Chicago Linguistics Solé, M.-J., & Recasens, D. (2012). The Society. initiation of sound change. Perception, Olmstead, A. J., Viswanathan, N., Aivar, production and social factors. M. P. & Manuel, S. (2013). Comparison of Amsterdam/Philadelphia: John Benjamins. native and non-native phone imitation by Stevens, M. (2012). A phonetic English and Spanish speakers. Frontiers in investigation into "Raddoppiamento sintattico" Psychology 4, 1-7. in Sienese Italian Speech. Bern: Peter Lang. Pardo, J. S., Gibbons, R., Suppes, A., & Stevens, M., & Reubold, U. (submitted Krauss, R. M. (2012). Phonetic convergence in manuscript). The parsing of pre- college roommates. Journal of Phonetics, 40, -aspiration in perception and production: 190-197. implications for sound change. Paul, H. (1888 [1886]). Principles of the Vinnik, E., Itskov, P. M., & Balaban, E. history of language. London: Swan (2011). Individual Differences in Sound-in- Sonnenschein, Lowrey & Co. Noise Perception Are Related to the Strength Perkell, J. S., Guenther, F. H., Lane, H., of Short-Latency Neural Responses to Noise. Matthies, M. L., Stockmann, E., Tiede, M., et PLoS ONE, 6(2), 1-8. al. (2004). The distinctness of speakers’ Warren, R. M., & Warren, R. P. (1971). productions of vowel contrasts is related to Some age differences in auditory perception. their discrimination of the contrasts. J. Acoust. Bulletin of the New York Academy of Soc. Am, 116, 2338. Medicine 47(11), 1365–1377. Weinreich, U., Labov, W., & Herzog, M. (1968). Empirical foundations for a theory of language change. In W. Lehmann & Y. Malkiel (Eds.), Directions for historical linguistics (pp. 95-198). Austin: University of Texas Press. Wretling, P., Strangert, E., & Schaeffler, F. (2003). Preaspiration as a quantity feature. Proc.15th ICPhS, Barcelona: 2701-2704 Yu, A. C. L. (2013). Individual differences in socio-cognitive processing and the actuation of sound change. In A. C. L. Yu (Ed.), Origins of Sound Change: Approaches to Phonologization. Oxford: Oxford University Press. 201-227. Yu, A. C. L., Abrego-Collier, C., & Sonderegger, M. (2013). Phonetic Imitation from an Individual-Difference Perspective: Subjective Attitude, Personality and "Autistic" Traits. PLoS ONE, 8(9), 1-13.