Wetensch. publicatieFaculteit der Lettere

Heuven, V.J.J.P. van

Zanten, E. van

Leiden University Scholary Publications

A Cross-Dialect Study of Vowel Perception in StandardIndonesianE. Van Zanten and V.J. Van HeuvenLeyden, the Netherlandsl. IntroductionShortly after World War II Indonesia gained its independence. One of thegovernmental acts was to impose one variety of Malay äs the official Stan-dard language, Bahasa Indonesia, throughout the archipelago. As a resultthe Indonesians now speak the Standard language (almost äs a secondlanguage) äs well äs a local vernacular, which though obviously related to theStandard language may differ from it in many respects. As a case in pointconsider the vowel Systems of the three vernaculars that are dealt with in thepresent paper:Toba Batak (5) Javanese (6) Sundanese (7)i u i u i y ue o e a o e 3 oa a aThe 6-vowel System of Standard Indonesian (disregarding diphthongs) isequal to that of Javanese. Toba Batak lacks the central mid vowel, whereasSundanese has two central vowels, viz. one mid and one high(er).In our study of the Indonesian vowel System we are interested in theacoustic and perceptual properties of the monophthongs, and the possibleinfluence of the regional Substrate on the subjects' performance. The presentpaper is confined to a perceptual experiment only.Our method is based on early work by Cohen, Slis and 't Hart (1963) on theperceptual tolerances of Dutch vowels, which was later successfully extended• to contrastive vowel studies by e.g. Scheuten (1975) and Hombert (1979). Inthese latter studies subjects were presented a large number of synthesizedisolated vowel sounds, regularly sampled from a vowel space essentiallydefined by F, and F2. Their task was to label each vowel sound in terms ofone of the vowels of their language. This method proved sensitive enough toreveal differences between the internal representation of British-Englishvowels of native Speakers and that of advanced Dutch learners of English(Scheuten, 1975). Hombert (1979) successfully applied the method to thedescription of the vowel Systems of a number of - strongly related - AfricanBantu languages. The issue at stake in our present study is whether theVan Zanten and Van Heuven: Vowel Perception in Indonesian 635labelling method will also reliably reflect differences between the vowelSystems of Speakers of a Standard language with different dialect back-grounds.2. MethodOn the basis of an acoustic pilot study (Van Zanten and Van Heuven, 1982),realistic formant ranges were defined for Indonesian vowels spoken inIsolation. A set of 188 monophthongs were then produced with a FonemaOVE Illb speech Synthesizer whose parameter values were controlled by aDEC PDP11/03 Computer. All vowels were given a 350 ms duration includ-ing linear onset and offset portions (in dB) of 50 and 100 ms, respectively.During the steady state portion voicing was set at maximum intensity. F, andF2 were systematically varied in steps of 9%, i.e. 3 times the Just NoticeableDifference commonly reported for F, and F2 centre frequency changes(Flanagan, 1955; Mermelstein, 1978; Nord and Sventelius, 1979), samplingthe acoustic vowel space in the way indicated in Fig. 1. F4 and F5 centrefrequencies were set at 3500 and 4000 Hz, respectively, for all vowels;bandwidths B1-B3 were set at mid-range values. The centre frequency of F3equalled that of F2 + 600 H2, with a minimum of 2460 Hz. Two tapes wereprepared containing the set of 188 Stimuli, preceded by a series of practiceitems, in counterbalanced random Orders.Three groups of Indonesians with different regional backgrounds partici-pated in the experiment: 4 Toba Batak, 5 Javanese, and 4 Sundanese listen-ers. All the subjects had completed a university education in their owncountry, and had only recently arrived in the Netherlands to enroll in apostgraduale program at the University of Leyden. They participated on avoluntary basis, and were paid for their Services.Subjects were instructed to label each vowel Stimulus äs one of the sixmonophthongs of Standard Indonesian (forced choice), and to rate eachtoken along a scale of acceptability: l (good), 2 (poor, but easily identifiable),3 (unacceptable and hardly identifiable).3. ResultsAfter having tried out various weighting procedures, the responses werefinally analysed such that 'good' tokens counted twice, 'poor' tokens once,and 'unacceptable' tokens were eliminated altogether. Figure l plots thedata for the three listeners groups (panel A: Toba Batak; panel B: Javanese;panel C: Sundanese). Areasofpreference were defined containing only thoseStimulus points that were identified äs one particular vowel in at least 50% ofthe responses (small letters), and in at least 75% (large letters). To facilitatethe exposition, summary statistics are given in Table I, specifying the numberof Stimulus points (absolute and relative) contained by each eara of prefe-rence.636 SociophoneticsSECOND FORMANT (Hz)·252.275,300,327,356.389,424462,504.550.599.654.713.777.848.924.1008.1 i . . u u u ui i " u u u u ul l i ' . ' . . , u u u | J U U U1 1 U U u u Ue e , , a , a . . , . o , .e e e , . 3 3 3 a . o o o oe e e . , . 3 a , , o 0 oe e , a θ θ , , , Ο ο οe e e oe e ee e . . . . . . o, a Q . .a Q a a Q Qα α a αα α α αPANEL A: TOBA BATAK LISTENERSFigure Ια. Distribution of responses to labelling lest for three groups of listeners. Panel A: TobaBatak, N = 4, äs afunctionof F^nd F2.4. Conclusions and DiscussionThere are several conspicuous differences across the three listener groups inthe locations and sizes of the preferred vowel areas, specifically in the way thecentral region of the vowel space is divided over the competing vowelphonemes. Typically, the /a/ area is small for the Toba Batak group,intermediate for the Javanese, and largest for the Sundanese. Conversely, thearea associated with /u/ is large for the Toba Bataks, intermediate for theJavanese, and smallest for the Sundanese.Van Zanten and Van Heuven: Vowel Perception in IndonesianSECOND FORMANT (Hz)637s2o252.275.300,327.356.389.i * . . ui i ι u u1 1 . . · u " u. . , , . . , , , , u LJe uUuuuuuUuuuuuuuuu462.504.550.599.654.713.777,848.924.1008.α α aα α αα α0 00 0α α α αPANEL B: JAVANESE LISTENERSFigure Ib. Distribution of responses to labelling lest for three groups of listeners. Panel B:Javanese, N = 5, äs a function of F, and F2.These differences in the distribution of the responses obviously reflectproperties of the subjects' regional Substrate languages. Remember that theToba Batak dialect has no central vowel, which explains why /s/ is the leastfavoured response category for the Bataks. Also, its area of dispersion ishighly irregulär, and only 2 out of 188 Stimulus points are identified äs /a/ inmore than 75% of the responses.For listeners with a Javanese background, an /a/ dialect, the preferredarea for /a/ is appreciably larger, and the responses are more regularlydistributed. For the Sundanese group, having a background dialect with twocentral vowels, the preferred /a/ area is larger still, and, perhaps more638 SocwphoneticsSECOND FORMANT (Hz)_O O cn oo252.275.300.327,356.389.1 1 i .1 1 ι1 1 i1 1 i» · > > . . ,. , , a , a aH-etOU_1—(ΛLL·462.504.550.599,654.713.777.848.924.1008.eeeeeeeee•e ,e ,e ee ee ee e3 3 a3 3 33 3 3e 3 3. a θ.1 . .a33a..(Ά αα αα α αα αα α° ο οο ο οο ο οοPANEL C SUNDANESE LISTENERSFigure lc Distribution ofresponses to labelhng lest for threegroups ofhsteners Panel C Sun-danese, N = 4), äs a function of F, and F2 Large letters represent Stimuli identified äs mdicatedby the phonetic symbol m at least 75% of the responses (after weightmg, see text), small lettersrepresent vowels identified with at least 50% agreementTable l Number of Stimulus pomts identified äs one particular vowel in at least 50% (75%) of theresponses, expressed absolutely and relatively, per vowel per group of subjects (4 Toba Bataks, 5Javanese, 4 Sundanese)Vowel 50% agreementBataks/!//e//a//o//u//a/unlabelled9221515251389( 5%)(12%)( 8%)( 8%)(13%)( 7%)(47%)Javanese8201920252076( 4%)(11%)(10%)(11%)(13%)(11%)(40%)Sundanese12201518172383( 6%)(11%)( 8%)(10%)( 9%)(12%)(44%)75% agreementBataks512115142139( 3%)( 6%)( 6%)( 3%)( 7%)( 1%)(74%)Javanese551311172135( 3%)( 3%)( 7%)( 6%)( 9%)( 1%)(72%)Sundanese7 ( 4%)11 ( 6%)H ( 6%)10 ( 5%)2 ( 1%)12 ( 6%)135 (72%)Van Zanten and Van Heuven: Vowel Perception in Indonesian 639importantly, here the distribution of especially /u/ is much more restricted:only 17 Stimulus points are identified äs /u/ with more than 50% agreement(against 25 for the other dialect groups), and only 2 with more than 75%(agaihst 14 and 17 for the Batak and Javanese listeners respectively). Presu-mably, the high(er) central vowel (which was not a response Option open tothe subjects) 'pushes back the /u/ boundary', i.e. precludes /u/ responses toStimuli with F2 values larger than 1000 Hz, whereas the preferred /u/ areaextends to 1100 Hz for listeners with a Javanese background (l neutralvowel), and even 1200 Hz for Toba Batak listeners (no central vowel).As a final observation we would like to point out a difference in overallperformance on the pari of the Javanese, äs opposed to the other groups: itappears that the properties of the Stimulus points that could not be adequate-ly identified (i.e. with at least 50% agreement) tends to be smaller for theJavanese (40%) than for either the Bataks (47%) or the Sundanese (44%).Summing up then, we have shown that the perceptual method of charting avowel System proved sensitive enough to reflect influences of the regionalSubstrates of listeners when asked to identify vowels in terms of the catego-ries given by their common national language.It also demonstrates that Speakers of a vernacular that is most similar tothe Standard language (in terms of the inventory of monophthongs) are in abetter position to reach high agreement (or: consistency) in the identificationtask than Speakers whose background dialect has a (marginally) richer orpoorer inventory.Finally, we advocate a wider use of the perceptual method outlined here tothe study of vowel Systems under conditions where sophisticated laboratoryequipment is not available for spectral analysis. The lest tape we haveprepared can be administered (to a large number of subjects in parallel, ifnecessary) in half an hour, and provides a wealth of easily interpretable andsurprisingly stable data.AcknowledgementsWork supported m pari by a grant from the Foundation for Lmguistic Research, funded by theNetherlands Organisation for the Advancement of Pure Research (ZWO) under project nr17-21-20; we thank Jos F M. Vermeulen for techmcal assistanceWe acknowledge the support of the Dept of Phonetics at the University of Utrecht by puttmgequipment at our disposalReferencesCohen, A , Shs, I H and Hart, J. 't (1963). Perceptual tolerances of isolated Dutch vowels.Phoneüca, 9, 65-78Flanagan, J L (1955) A difference hmen for formant frequency. Journal of the AcousticalSociety of America, 27, 613-617.Hombert, J-M. (1979) Universals of vowel Systems, the case of centrahzed vowels. In: E.Fischer-J0rgensen, J. Rischel, N. Thorsen (eds ). Proceedings of the Nmth InternationalCongress of Phonetic Sciences, Vol II Institute of Phonetics, Copenhagen, 27-32.640 SociophoneticsMermelstem, P (1978) Difference hmens for formant frequencies of steady state and conso-nant-bound vo\yels Journal of the Acoustical Society of America, 63, 572-580Nord, L and Sventelius, E (1979) Analysis and prediction of difference hmen data for formantfrequencies Phonetic Expenmental Research at the Institute of Lmgmstics Umversttyof Stock-holm, Report I Experiments in speech perception, Phoneilcs Research Seminar 1978-1979,24-37Scheuten, M E H (1975) Native-language mterference in the perception of second-languagevowels, Doct Diss University of UtrechtZanten, E Van and Heuven, V J Van (1983) A phonetic analysis of the Idonesian vowelsystem a prehmmary acoustic study NUSA, Lmguistic Studien in Indonesian and other Lan-guages in Indonesia, 15, 70-80

A cross dialect study of vowel perception in Standard Indonesian

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A cross dialect study of vowel perception in Standard Indonesian

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