ALLOPHONE RECOGNITION FOR L2 LEARNERS: PATTERN ?· ALLOPHONE RECOGNITION FOR L2 LEARNERS: PATTERN MATCHING…

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<ul><li><p>Lagos Papers in English Studies Vol. 1: 1-19 (2007) </p><p>July - 2007 1 </p><p>ALLOPHONE RECOGNITION FOR L2 LEARNERS: </p><p>PATTERN MATCHING OR RULE-BASED EFFECT? </p><p> CHRISTOPH HAASE </p><p>CHEMNITZ UNIVERSITY OF TECHNOLOGY </p><p> Partaking in the discussion of learner abilities in a second language we try to solidify a notion of interlanguage that holds not only from an acquisition point of view but also typologically, rendering interlanguage a "proper" language in certain areas. For this, allophonic variation of aspirated and unaspirated stop consonants has been studied in its effect on perception of highly competent L2 learners. Learners were expected to show inhibited performance due to a lack in discriminating competence. This lack is not acquired but a feature of the interlanguage which therefore shows typologically plausible gaps in the stop system. The study demonstrates insight into the learner's phonological model of a target language and makes some predictions about extent and limitations of their auditive performance. </p><p> 1. Introduction The acquisition of phonological subtleties in a second language is subject to a variety of influences of which rapidity (speaking rate), phoneme separation and noise are parameters, separation in part being a function of rapidity. The listener needs the resource of time in order to process the phonetic signal. This timespan can be considered as depending on competence which represents a parameter that merits further investigation when set to correlate with learner performances. Another parameter of complexity of the speech signal is coarticulation (e.g. Miller, 2001): any phoneme carries more information for the specific segment; cf. the /k/ in /ki.p/ (keep) is different to the one in /ku.l/ (cool). However, as can be observed stably, second language learners simplify in articulation, but likewise their audition is comparatively impaired. It takes time until learners start to "hear" differences, to tune and successively readjust their phonological competence to levels beyond mere intelligibility. Although the production of velar stops for L2 learners of English with first language German can be considered straightforward and unproblematic as far as intelligibility is concerned, usage conforming to rules of English phonology is not. Together with [voice] the second laryngeal feature, [aspiration], has a distinctive function in the respective language (Brown 1998: 141). A contoid (i.e. a consonant in its phonetic characterization) can be aspirated in that the voiceless contoid is followed by a voiceless lenis laryngeal approximant. In English aspiration is phonetic for single words: pin /'p.n/ ['p..n]. This is also the case with German zehn (ten) (/'tse.n/ ['t.se.n]) but not in Mandarin </p></li><li><p>Lagos Papers in English Studies Vol. 1: 1-19 (2007) </p><p>July - 2007 2 </p><p>Chinese, where aspiration is phonological (Canepari 2005: 203) and not in Cuzco Quechua, where aspiration is not only phonological but also part of a three-way distinctive laryngeal node feature with aspirated, unaspirated and glottalized stops (Parker/Weber 1996: 75). The Quechua word tanta has therefore three lexical entries: /tanta / [tanta] -collection, /tanta/ [tanta] - bread and /t.anta/ [t.anta] old, used up (ibid.). Further, English and German differ from other languages that also have preaspirated stops in the way they employ laryngeal contrasts in connected speech. In Russian and Hungarian for example this can be captured as a two-way [voice] contrast, in German it is [spread] and in English (together with Swedish and Russian) it is [voice] and [spread], cf. Petrova et al., (2006). This contrast is to a lesser extent noticeable in English as a second language. What is observable is a certain carelessness of advanced second language speakers and a subsequent difficulty to imitate and apply. In this study, tables have turned for the speakers insofar as only the perceptional side is considered. Subjects were asked to deduce the rule that governs aspiration in velar stops of which English has a richer system as German or French, in comparison. The experiment follows suggestions made in a landmark study by Jaeger (cf. Jaeger 1980) and revisited by Ohala (Ohala 1982: 237) and considers more current results by Whalen/Best/Irwin, 1997, Best/McRoberts, 2003 and Kingston, 2003. In the final part, we sketch a perspective on the phonological acquisition of second language learners and investigate second language parameters against results obtained by Best (Perceptual Assimilation Model, PAM), Best 1994. Aspiration has been selected as a parameter as it provides a clear-cut binary feature. There is one exception to this: When stress is also considered, then aspiration is strongest in syllableinitial positions of stressed syllables (Giegerich 1992: 219). This has been observed early, cf. Trubetzkoy who describes that a 1-dimensional opposition between phonemes of the same obstructional level renders particular correlations (1989[1939]:138). Although non-distinctive in English as well as in German, the opposition provides a testing ground for auditive competence of L2 speakers of English with advanced competence. Although e.g. [p] and [p.] do not form minimal pairs and do not occur in the same environment (Hyman 1975: 62), English is particularly rule-governed when it comes to aspiration, a circumstance this study makes use of. 2. Aspiration: The phonological and typological perspective Aspiration affords higher energy when it is produced to accompany a stop sound as it involves a somewhat stronger puff or burst of air. The articulatory background can be found in the feature of [-spread glottis] for unaspirated stops (e.g. Vaux 1998: 497) and respectively [+spread glottis] for aspirated stops. In a simplified way, the burst of air can therefore be explained as a glottal phenomenon where the glottis opens for a brief moment to leave a gap for the airstream to pass, which is the case especially in voiceless consonant </p></li><li><p>Lagos Papers in English Studies Vol. 1: 1-19 (2007) </p><p>July - 2007 3 </p><p>speech sounds [p], [k] (cf. Giegerich 1992: 3). This explanation, however, ignores the existence of aspirated voiced stops as [b.]. Aspiration is therefore often seen as a weakened intermediate step in the spirantization of plosives (Dogil/Luschtzky 1990: 37). Hence, the glottis involvement must be more divergent. A time course consideration of the glottis makes obvious that the timing of glottis movement is crucial. Differences in aspiration are measured as a function of the amount of air ejected. Quantity of aspiration is therefore commonly defined as delay in the onset of the vibration of the cords after the release of a preceding voiceless consonant /p.at / vs. /spat/ (Kenstowicz/Kisseberth 1979: 10). This means that for unaspirated stops the occlusion is released simultaneously with the voice onset (Clark/Yallop 2002: 53) whereas for aspirated stops the voice onset follows the release with a short but discernible delay. Accordingly, the phonological features accompanying aspiration are laryngeal features. Of the two laryngeal features, one controls glottalization [+constricted gl], the other aspiration [+spread gl] (Kenstowicz 1994: 493). This also means that both features cannot occur at the same time for the same speech segment, they are incompatible, cf. also Paradis/LaCharite 2001: 291. On the other hand, Kenstowicz sees only few or no constraints on [- constr gl] or [- spread gl] (ibid) which creates a certain asymmetry for any categorization which is confined to positive (+) variants of the respective features. 2.1. Rules governing aspiration in English </p><p>The aspiration rules in English must be subdivided according to the concerning stop consonant although they share some common features. Even though English lacks words that would substitute aspirated [p] for unaspirated [p], aspirated [p] always occurs in certain positions in a word, like word-initial or syllable-initial positions whereas unaspirated stops occupy positions in the middle of words or ends of syllables. Conversely, Kenstowicz and Kisseberth conclude that unaspirated voiceless stops occur in noninitial position (Kenstowicz/Kisseberth 1979: 30), aspiration of voiceless stops in initial position in monosyllabic words is even an invariable correlation (ibid.). This statement however, can not be made for all environments. Kenstowicz observes further, that a preceding [s] deprives voiceless stops of all aspiration as in [spat] (ibid: 257). Here, lip closure from [p] coincides with the onset of the vowel, there is no discernable delay, the stop comes out unaspirated. If a stop consonant is aspirated or not is therefore not completely predictable from context in English (Caplan 1987: 202). Furthermore, attention has to be paid to the distribution in bi- or polysyllabic words and the presence or absence of stress. It is therefore possible to formulate a rule for the distribution of aspiration in English stops. The obvious difference enables native speakers effortlessly to articulate according to the rule: In English, voiceless stops are generally aspirated, except after /s/ and before unstressed vowels, where they are unaspirated. (Crowley 1992: 220). The full system of English aspirated and unaspirated stops is more complex. Although Clark and Yallop maintain that </p></li><li><p>Lagos Papers in English Studies Vol. 1: 1-19 (2007) </p><p>July - 2007 4 </p><p>unaspirated initial stops besides their distribution in German and Dutch do occur in certain dialects in northern England (Clark/Yallop 2002: 52), the canonical system for English looks as follows: English has a 4 (6)-way system, cf. Vaux 1998: 497: b. p p. d d. t t. g g. k k. Deviations from this are dialectal as well as variational: Scottish Standard English exhibits the weakest aspiration of all distinctive varieties of English (Giegerich 1992: 219). Gaps in the system like the missing unaspirated [b] are not uncommon (Clark/Yallop 2002: 124), uncommon however are fully-fledged systems that exhibit all possible stops in aspirated as well as unaspirated variation. The marking of aspiration modifies the time course of the stop articulation. Unaspirated stops occupy very short durations of about 10-15 ms, aspiration extends this duration up to about 50 ms (Fry 1987: 122). Measurements in the experiment described here clocked 18 ms for [k] and 56 ms for [kh], cf. waveforms fig. 1 and fig. 2. 3. Hypotheses and assumptions </p><p>With the experimental setup suggested here, our study of learner subject perception performance aims at several different propositions. First, some assumptions are made about aspiration in interlanguage competence and ways to consider learner interlanguage as part of a typological spectrum that includes a solid if incomplete system of aspirated speech sounds. Second, differences in perception performance are related to the inference of rules out of stimuli on basis of a first language. </p><p>3.1. Aspiration in learner interlanguage The idea of interlanguage as brought forward by Selinker among others from 1972 onward is a program to map the progress to proficiency of second language learners. According to Selinker, interlanguage is a structured system a learner constructs during acquisition (Ellis 1992: 42). This system underlies processes of transfer, overgeneralization and instructed rules and is thought of as a continuum, the end of which yields competence in a second language. Moreover, it does not become clear if competence is part of the continuum or the end of it which leaves the question if competence itself is a continuum. Arguably, all these processes are processes of simplification. At any state, however, rules are considered to be in flux where the rule system is considered open instead of closed. Open phonological rules would generate a random, erratic behavior of test subjects as it is open to debate whether interlanguage in Selinkers definition is comparable at all. However, Ellis maintains that interlanguage is systematic even though he states that free variation occurs which leads to learner performance that varies from task to task. The criteria mentioned above make interlanguage look like an ad hoc device that does not resemble natural language to a large extent. This is however implausible given that learners end up with L2 competence. Calling it interlanguage therefore invites criticism and debate. If however Selinker's notion of interlanguage is true that L2 learners reactivate latent language </p></li><li><p>Lagos Papers in English Studies Vol. 1: 1-19 (2007) </p><p>July - 2007 5 </p><p>structure and subsequently employ the same cognitive mechanisms and devices responsible for first language acquisition then these same mechanisms will determine their internal phonological representation and thus inhibit their performance. As Corder maintains, 95% of all learners stop before reaching the end of the interlanguage continuum - native-like competence - and fossilize at a certain stage, phonological fossilization would be only one component and a logical outcome of second language acquisition. As a starting hypothesis, L2 learners of the studied type have a strong bias towards unaspiration as their interlanguage underlies transfer effects that are not compensated or overruled by instruction. As interlanguage usually omits elements that are non-essential for communication (Cook 1993: 40) aspiration looks negligible at first glance. Even at second glance the feature is produced by imitation only as there is no physiological necessity to aspirate (Kenstowicz/Kisseberth 1979: 30). Accordingly, the question why aspiration occurs at all is sometimes considered epiphenomenal and outside phonological theory (Giegerich 1992: 292p.). In 5. we will make some assumptions of origin and scope of aspiration within a general theory of phonation. 3.2. Hypotheses on aspiration perception of L2 learners </p><p>Learners and native speakers use considerably different acoustic-phonetic cues to segment speech and to perceive word boundaries. Often, perception of differences between e.g. keep sticking and keeps ticking (from an experiment in Altenberg 2005: 331) is severely inhibited for L2 learners. Several parameters were identified to inhibit the perception of segmentation (longer /s/ with higher amplitude in sticking, longer closure in keep than in keeps) but primarily the segmentation can be related to the perception of aspirated /t./ in ticking versus unaspirated /t/ in sticking, or more general, aspiration [is] a primary cue in English speech segmentation (ibid: 328). Acquisition is a mapping of abstract implicational rules onto concrete speech. Ohala maintains in this respect, that occurrences of allophones would be grouped into phonemes (1982: 236) according to parametrized learning. However, establishing these parameters is difficult and unstable across languages. On the other hand, other researchers see a general principle where stimulus concreteness is mediated by cognitive processes...</p></li></ul>