Chinese subjects'perception of the word-final English/t/-/d/ contrast: Performance before and after training James Emil Flege Departmentof Biocommunication, Unioersity of A!abamaat Birmingham,Uniuersity Station. Birmingham, .4 labarea 35294 (Received8 August 1988;accepted for publication20 July 1989) Chinesewords may beginwith/t/and/d/, but a/t/-/d/contrast doesnot existin word-final position.The questionaddressed by experiment1 waswhether Chinese speakers of English couldidentify the final stopin wordslike beatand bead.The Chinesesubjects examined approachedthe near-perfect identification rates of nativeEnglish adults and children for words that wereunedited, but performedpoorly for wordsfrom whichfinal release bursts had been removed.Removing closure voicing had a smalleffect on the Chinesebut not the English listeners'sensitivity. A regressionanalysis indicated that the Chinesesubjects' native language (Mandarin, Taiwanese,Shanghainese) and their scoreson an Englishcomprehension test accountedfor a significantamount of variancein sensitivityto the (burstless)/t/-/d/ contrast.In experiment2, a small amountof feedbacktraining administeredto Chinese subjectsled to a small, nonsignificantincrease in sensitivityto the English/t/-/d/contrast. In experiment3, more training trials were presentedfor a smallernumber of words.A slightly larger and significanteffect of training wasobtained. The Chinesesubjects who were native speakersof a languagethat permitsobstruents in word-finalposition seemed to benefitmore from the trainingthan those'whosenative language (L1) hasno word-finalobstruents. This wasinterpreted to meanthat syllable-processingstrategies established during L 1 acquisition may influencelater L2 learning. PACS numbers: 43.71.Es, 43.71.Hw INTRODUCTION aL, 1981;Werker and Tees, 1983, 1984a,b).An apparent consequenceof this lost ability is the difficultyadults may Much secondlanguage (L2) acquisitionresearch has havein comprehendingan L2 later in life (Johansson,1978; beenmotivated by the desireto learnwhether a biologically van Balen, 1980;Oyama, 1982b;Florentine, 1985;Koster, (rather than cognitively)based "critical period" exists for 1987;Mack and Tierney,1987). Suchcomprehension diffi- humanspeech learning. Lenneberg ( 1967,p. 176) claimed culty may derive,at leastin part, from difficultyperceiving that "foreignaccents cannot be overcomeeasily after pu- phonesin the L2. berty."Rating-scale experiments have amply comfirmed the EchoingTrubetzkoy's (1939) observationthat the pho- presenceof foreignaccents in the speechof L2 learners,even nologyof L1 actslike a "sieve"through which L2 •unds are thosewho began learning L2 longbefore the onset of puberty processed,Borden et al. (1983} suggestedthat adult L2 (Asher and Garcia, 1969;Fathman, 1975; Flege and Eeft- learnersare "constrained"to categorizethe phonesof an L2 ing, 1987;Flege, 1988a,b; see also Seliger etal., 1982).1 The "accordingto the phonemecontrasts" of.their native lan- mispronunciationof particularphones, which contributes to guage(p. 500}. This mightexplain why, for example,Japa- foreign accent (see Johansson,1978; F!ege, 1984, 1988a; nesespeakers have difficulty in discriminatingEnglish/r/'s Schneidermanet al., 1988), may derivein part from insuffi- and/1/'s (Miyawaki et aL, 1975). It doesnot explainother cientmotor learning.This, in turn, may be impededby an experimentalevidence so well, however.Flege and Hillen- inability to perceiveL2 phonesor phoneticcontrasts in a brand (1985) found that Swedesand Finns, whoseL 1 hasno nativelikemanner. Difficulty distinguishing phonemes in an /z/, were able to differentiallyidentify the membersof a L2 mayalso impede lexical development (see Leonard et al., continuumranging from peace (/pis/} to peas(piz). They 1982). The purposeof the presentstudy was to provide usedonly vowel duration, however, whereas native speakers further insight into how phonesin an L2 are perceivedby of English used a combination of vowel and fricative dura- examiningthe perception of thevoicing feature in word-final tion cues. Englishobstruents. The presentstudy examinedthe identificationof final Prelinguistieinfants are able to discriminatemany, if /t/ and /d/ by Chinesesubjects. The Ll's of the subjects notall, of the.phonesused contrastively in human languages examinedpossess a contrast between phonologieally voiced (see,e.g., Jusezyk, 1979; Kuhl, 1987), but thisability maybe andvoiceless stops, but only in word-initialposition (Cheng, attenuated near the end of the first year of life for certain 1973;Howie, 1976;Li and Thompson,1981; Shinn, 1985; phoneticcontrasts. Werker and her colleaguesfound that Heyer, 1986). The word-initial phonemiecontrast in Chin- young children lost the ability to discriminatephones not eseis implementedas a phoneticcontrast between voiceless usedcontrastively in the languagespoken around them, even unaspiratedstops with short-lagvoice onsettime (VOT) though they were able to do so earlier as infants (Werker et valuesand voicelessaspirated stops with long-lagVOT val- 1684 J. Acoust.Soc. Am. 86 (5), November1989 0001-4968/89/111684-14500.80 ¸ 1989 AcousticalSociety of America 1684 ues(Lisker and Abramson,1964; Clumeck eta!., 1981). theycontained some of the informationthat cues the voiced- Littleis known about how Chinese subjects perceive fi- voicelesscontrast in word-initialposition. Such a strategy nal stopsin English,but much is knownabout how they could be expectedto work lesswell for stopsfrom which produce word-final stops.As predicted by the contrastlye releasebursts had been removed,however. Alternatively, analysishypotheses (Lado, 1957), Chineselearners of Eng- the Chinesesubjects might regardword-final tokens of/t/ lishare oftenunable to producea perceptuallyeffective con- and/d/as representinga "novel" phoneticcontrast, and trast betweenvoiced and voicelessstops in word-finalposi- begin seekingcues other than those used for word-initial tion. Transcriptionaldata from severalstudies have shown stops,such as precedingvowel duration. If so, the Chinese that Chinesespeakers devoice English/b,d,g/, deletevoiced subjectsmight perform more poorly than the native English and voicelessstops, and/or add vowelsfollowing word-final subjectsfor the tokenswith releasebursts, but the effectof stops(Tarone, 1980;Eckman, 1981; Anderson, 1983, 1987; removingrelease burst (and closure voicing) cues should be F!egeand Davidian, 1985;Heyer, 1986;Weinberger, 1987; no greaterfor them than for native Englishsubjects. Flegeet al., 1987). Detailed analysesof the productionof The resultsof experiment1 supportedthe first alterna- /p/ and/b/ in word-finalposition have shown that Chinese tive, so two feedbacktraining experiments were carried out subjectsproduce a much smaller(albeit significant)dura- to betterenable the Chinese subjects to perceivethose cues to tion differencebetween vowels preceding/p/vs/b/, are the/t/-/d/contrast that remainedafter the closurevoicing significantlyless likely than nativespeakers to activelyen- and releaseburst cueshad beenremoved. The first training largethe oral cavityto sustainvoicing in/b/, and do not experimentinvolved subjects who had participated in exper- produce/p/with a greaterforce ofbilabial constriction than iment1. A greateramount of feedbacktraining was present- /b/(Flege eta!., 1987;Flege, 1988e). edin thesecond training experiment to a newgroup of Chin- Thesefindings show that the ability to producevoiced esesubjects. A "neural atrophy" hypothesis(see Werker andvoiceless stops in word-initialposition does not guaran- and Tees, 1984b) impliesthat it would be difficultto in- teethe ability to producean effectivevoiced-voiceless con- creaseChinese subjects' sensitivity to the/t/-/d/contrast trast in the word-final position.This suggeststhat speech throughshort-term laboratory training. The notionthat au- productionis not basedon freely cornmutablephoneroes ditory sensitivityis neverreally lost,but is simply"difficult { seeFlege and Port, 1981) and that speechproduction skills to apply"to novelphonetic contrasts as the resultof a "lan- must be learnedon an allophone-by-allophonebasis (see guagebased reorganization" of contrastlyesound units also Bri•re, 1966). This inferenceis consistentwith the ob- (Werker, 1989) suggestsa differentoutcome, however. servationthat soundsmay be morevulnerable to disruption Trainingmight be effective if it succeedsin enablingsubjects in initial than final positionfollowing injury to the brain topay attention to relevantacoustic cues ( Strange,1986), or (Kent and Rosenbek1983; Kelso and Tuller, 1981). It is if it helpssubjects engage a phonetic,as opposed to a phone- alsoconsistent with the conclusion,based on performance mic,mode of processing(Werker and Tees, 1984b}. errors in normal individuals, that word-initial consonants areprocessed separately from subsequent consonants (Shat- I. EXPERIMENT 1 tuck-Hufnagel,1987). A. Introduction The questionaddressed by experimentI was whether speechperception skills also need to be learnedon an allo- The closureintervals of Englishfo,d,g/and/p,t,k/are phone-by-allophonebasis. To determinethis, nativeand distinguishedby thepresence versus absence of voicingdur- Chinesesubjects were asked to identifythe finalstop in une- ingoral constrictionin isolated,clearly spoken words, but as ditedmultiple natural tokens of Englishwords such as beat a rule voicingdoes not extendthrough the entireconstric- and bead,and in copiesfrom whichthe final releasebursts tion of/b,d/g/. As discussedlater (seealso the Appendix), and/or