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Regional Dialect Variation in the Vowel Systemsof Typically Developing ChildrenEwa Jacewicz,a Robert Allen Fox,a and Joseph Salmonsb

Purpose: To investigate regional dialect variation in the vowelsystems of typically developing 8- to 12-year-old children.Method: Thirteen vowels in isolated h_d words were produced by94 children and 93 adults (males and females). All participantsspoke American English and were born and raised in 1 of3 distinct dialect regions in the United States: western NorthCarolina (Southern dialect), central Ohio (Midland dialect), andsoutheastern Wisconsin (Northern Midwestern dialect). Acousticanalysis included formant frequencies (F1 and F2) measuredat 5 equidistant time points in a vowel and formant movement(trajectory length).Results: Children’s productions showed many dialect-specificfeatures comparable to those in adult speakers, both in termsof vowel dispersion patterns and formant movement. Different

features were also found, including systemic vowel changes,significant monophthongization of selected vowels, and greaterformant movement in diphthongs.Conclusions: The acoustic results provide evidence for regionaldistinctiveness in children’s vowel systems. Children acquirenot only the systemic relations among vowels but also theirdialect-specific patterns of formant dynamics. Directing attentionto the regional variation in the production of American Englishvowels, this work may prove helpful in better understandingand interpreting the development of vowel categories and vowelsystems in children.

Key Words: dialect acquisition, regional vowel systems,formant movement

A coustic characteristics of AmericanEnglish vow-els have been widely studied since the seminalwork by Peterson and Barney (1952). However,

only relatively recently has sociophonetic research rec-ognized that vowels in American English differ greatlyin terms of their spectrotemporal characteristics acrossdialect regions in the United States. Regional variationin vowels has been identified and documented primarilyin the speech of adults, and to date, there is still no com-prehensive account of regional influences on the develop-ment of vowel systems in children. This article addressesthis issue by investigating the extent to which regionalvowel features found in adults are present in productionsof typically developing 8- 12-year-old children. In so do-ing, this study aims to determine the strength of dialect-specific features in children and to illuminate which

vocalic dialect features become permanent parts of achild’s accent or dialect.

By means of acoustic analysis, the study examineswhether and towhat extent children acquire not only thedialect-specific relative positions of vowels in the two-dimensional F1 ×F2 plane but also their dynamic formantfrequency patterns. As recent research shows, vowels arenever truly static and exhibit at least some amount ofvowel-inherent spectral change (e.g., Nearey&Assmann,1986; Watson &Harrington, 1999). This spectral change,also called dynamic formant movement, has been foundto differentiate vowel variants across regional dialects ofAmerican English (Fox & Jacewicz, 2009). Moreover,cross-dialectal differences have been found both in vowelduration (Jacewicz, Fox, &Salmons, 2007) and in speechtempo (Jacewicz, Fox, O’Neill, & Salmons, 2009; Jacewicz,Fox, & Wei, 2010), both of which affect vowel dynamics,including the spectral rate of change in a vowel (Fox &Jacewicz, 2009). To what extent do children acquire thesedialect-specific dynamic vowel characteristics?

Regional Variation in Phonetic Inputto Children

When learning vowel systems in their first language,children are usually exposed to highly variable input from

aThe Ohio State University, ColumbusbUniversity of Wisconsin—Madison

Correspondence to Ewa Jacewicz: [email protected]: Anne SmithAssociate Editor: Melanie Matthies

Received June 11, 2010Accepted September 8, 2010DOI: 10.1044/1092-4388(2010/10-0161)

Journal of Speech, Language, and Hearing Research • Vol. 54 • 448–470 • April 2011 • D American Speech-Language-Hearing Association448

speakers in their speech communities. Typically, this in-put represents a form of a regional variety (or dialect) ofthe language spoken in a specific geographic area. In theUnited States, these regional varieties have been docu-mented and characterized in the Atlas of North Ameri-can English (Labov, Ash, & Boberg, 2006), which definesAmerican dialect regions on the basis of a variety of dif-ferences but with an overwhelming focus on vowels. Abroad body of sociolinguistic research provides strong evi-dence that regional variation is always present in spokenutterances, and some researchers argue that the notionof general Standard American English should be aban-doned. As an example,WolframandSchilling-Estes (2006)point out that “the definition of spoken standardAmericanEnglish is a flexible one, sensitive to regional variation,stylistic range and other social variables” (p. 324). Thisimplies that children growingup in a given geographic re-gion are destined to acquire features of the local dialect.

However, evenwithin a regionally defined variety ofEnglish, there is great variability in the input availableto children. The children’s acquisition of language typ-ically begins with their mother ’s vernacular and hervowel system. The view that female caretakers are the pri-mary source for first language learning has particularlystrong support in sociolinguistic research (see Chapter 9of Labov, 2001). After the first few formative years, how-ever, children learn to talk differently from their moth-ers (and from their caregivers in general) and adopt theemerging patterns of their speech communities. In fact,as pointed out by Labov (2010b), children have the ca-pacity to detect the sound systemof their speech commu-nity and begin to prefer this system over that which theyfirst acquired from their caretakers. This continuous pro-cess of learning and reorganizing was defined by Labov(1994) as transmission (i.e., transfer of features fromadultsto children) and incrementation (i.e., the mechanism bywhich changes advance in a step-by-step fashion).

The variability in the input available to children intheir speech communities comes in part from the fact thatadults, adolescents, and children’s peers differ in the de-gree and type of regional characteristics present in theirspeech and that some individuals speak with “stronger”regional accents than others. Yet, the incrementation oflanguage change comes about by children’s awarenessthat differences in language use (variants) are associatedwith the age of the speakers and that, specifically, “theyounger the speaker, the more advanced the change”(Labov, 2007, p. 379). This indicates that older childrenwho already passed their first formative years begin toturn to their peers as the more “proper” target for theirlanguage learning.

Two different accounts have been presented in re-cent research for how patterns of regional variation arechanging today, and evidence exists for both. First,much

research onAmericanEnglish (reviewed inLabov, 2010a;Labov et al., 2006) finds an increasing divergence of NorthAmericandialect regions, and this view isnowwidespread,if not ubiquitous, among sociolinguists and dialectologists.At the same time, variability in the input increases withpopulationmobility, exposing learners to new and broadersets of inputs. The second line of research focuses spe-cifically on the effects of language contact, studying theacquisition of second dialects—that is, acquisition of di-alects or dialect features by individualsmoving from oneregion to another (e.g., Chambers, 1992, 2003; Kerswill,1996; Payne, 1980; Rys&Bonte, 2006). Because regionalvariation as a function of language contact is not of im-mediate relevance to the present study, this research isnot discussed further here. Supplemental material canbe found in Foulkes andDocherty (1999), Kerswill (1994,2003), Salmons and Purnell (2010), and Trudgill (1986,2004), among others.

Acquisition of Dialect FeaturesThe presence of interspeaker variation in the input

poses a number of questions related to the acquisition ofregional dialect features by children. Most importantly,to what extent are children able to adopt and reproducethe dialect features typical of a given speech communityin the midst of highly variable input? As posited by theLabovian model of transmission and incrementation,the initial input provided by primary caregivers from thearea constitutes a strong source of regional variants (seealso Roberts, 2002, for a discussion of the importance ofearly input to children). Strong dialect-specific featuresare oftenpresent in the speechof older adultswhogrewupin the area, who did not travel as extensively as youngergenerations, and who have maintained close ties withother members of the community. However, newcomerswho move into the region can constitute an influentialsource of nonlocal linguistic forms. This is reported to beparticularly important amongpeers duringpreadolescenceandadolescence (e.g., Eckert, 1999). Labov (2001) hypoth-esizes that “most linguistic influence is exerted in earlyand middle adolescence,” the end of the opportunity for“vernacular reorganization” (p. 502). Therefore, it is ofinterest whether children continue to participate in thetransmission of dialect-specific features or adhere to thenew (or converged) forms introduced to the area.

To address this and related issues for AmericanEnglish,Roberts studied theacquisitionof selecteddialect-specific phonological markers by young preschool chil-drenwhowere growingup inPhiladelphia (Roberts 1997a,1997b; Roberts & Labov, 1995). In Roberts and Labov(1995), the acquisition of the Philadelphia short /A / wasexamined in light of complex conditioning factors comingfrom lexical, phonological, and grammatical constraints.

Jacewicz, Fox, & Salmons: Regional Dialect Variation in Children’s Vowels 449

Thequestionwaswhetherpreschool children could detectand learn this dialect-specific complexity and reproducethe dialect-specific variation in the pronunciation of /A /.The study showed that children between the ages of 3and 4 were able to acquire the complex rules and werealso found to participate actively in the process of /A /-change in specific consonant environments. In anotherstudy, Roberts (1997a) examined the pattern of variabil-ity in deletion of final /t/ and /d/ in word-final consonantclusters in Philadelphia children (3 and 4 years old). Al-though the /t, d/ deletion has been studied extensively insociolinguistic research providing arguments for develop-mental, social, and dialect-specific influences in Englishworldwide (e.g., Bayley, 1994; Guy, 1980; Patrick, 1991;Smith, Durham, &Fortune, 2009; Tagliamonte& Temple,2005), Roberts’ data showed that children learned andmatched the adult Philadelphia-specific pattern. Thatis, they demonstrated acquisition of the variable rulesof dialect-specific /t, d / deletion rather than adheringto more global developmental or social effects. Finally,Roberts (1997b) found further support for dialect-specificpatterns of changes in the diphthongs /aI/ and /aO/ as infight, right, mice, cow, crown, and south produced by pre-school children, which also underscores the importanceof early input provided by Philadelphia-native parents.

Dialect-related variability in American English vow-els and, specifically, variability of formant frequency pat-terns in vowel production in childrenhasnot been studiedas systematically as have other phonological markers.Children’s data are of particular interest in examiningdialect-specific vowel shifts and changes (which have beenidentified in the production of adults) because of their po-tential role in language change (see Labov, 2001, chap-ters 13 and 14). However, the existing reports are rathersparse, and data are presented mostly from individualspeakers. For example, Labov (1994) provides illustra-tive charts of the vowel systems of several teenagers andonly two children, one 11-year-old female (p. 108) and one13-year-old male (p. 100). To date, there is no detailedacoustic study of variation in American English vowelsproduced by children across a wider age range as a func-tion of regional dialect.

Regional Dialects and Vowel FormantPatterns in Children

Most of the detailed acoustic data examining vowelproductions across dialect regions in the United States(Clopper, Pisoni, & de Jong, 2005; Hagiwara, 1997) comefrom young college-age adults as participants. A muchwider range of adults, including very old speakers, haveparticipated in Thomas’ regional survey (Thomas, 2001)and in Labov ’s lifetime work on regional variation inAmerican English (most notably, Labov et al., 2006).

Another acoustic study by Hillenbrand, Getty, Clark,and Wheeler (1995) used speakers from the upper Mid-west, mostly from Michigan, including children ages10–12 years. However, the goal of the work was to rep-licate the classic study by Peterson and Barney (1952),which also included children, and not to inquire into re-gional variation in children’s speech.

Alternatively, acoustic studies thathave explored chil-dren’s vowel production have been primarily concernedwith documenting developmental patterns in children, in-cluding gender differences, comparedwith those in adults(e.g., Assmann & Katz, 2000; Bennett, 1981; Busby &Plant, 1995; Lee, Potamianos,&Narayanan, 1999; Perry,Ohde, & Ashmead, 2001; Whiteside & Hodgson, 2000;Whiteside, 2001). The children used in these studieswere preadolescent girls and boys ranging in age from5 to 12 years, variously divided into narrower age groups,depending on the research focus. Their language back-ground was usually reported as Standard American orAustralian English, although some researchers did pro-vide specific information about geographic regions inwhich their participants were born and raised (for Amer-icanEnglish: Assmann&Katz, 2000, Bennett, 1981; andLee et al., 1999; for British English:Whiteside&Hodgson,2000). In terms of selected developmental factors, the datain Whiteside (2001) indicate most clearly that gender-related differences in formant frequency values emergeat age 10 years (which may reflect the beginning of thedevelopmental prepubertal stage at approximately age10 years proposed by Fitch and Giedd [1999] indicatinggender-related anatomical changes in the vocal tract), butthese differences vary for specific formants and specificvowels.

Researchers are becoming increasingly aware thatdialect background should be considered in the inter-pretation of the formant frequency data in vowels fromboth adults and children. Although regional variation inadults can be evaluated by including the effects of dialectas a variable in cross-dialect comparisons because mini-mal developmental factors are involved, understandingchildren’s productions requires careful examination ofboth developmental effects (related to age and gender)and possible dialect variation, which may confound theinterpretation of developmental changes. Vorperian andKent (2007, p. 1514) address this very issue in their re-analysis of formant frequency data from 14 differentsources that reported children’s formant values. Admit-ting the confounding effect of dialect, they also state,“One reason why dialectal influence was difficult to con-trol is because the formant-frequency data used in thisstudywere published overan interval of nearly 5decades,and dialects shift over time” (p. 1514).

Vowel change inEnglish is systemic in nature and hasbeen widely documented in phonetic studies of American,

450 Journal of Speech, Language, and Hearing Research • Vol. 54 • 448–470 • April 2011

Australian, British, and New Zealand English dialectsin speech of adults (e.g., Cox, 1999; Gordon, Campbell,Hay, Maclagan, Sudbury, & Trudgill, 2004; Kerswill,Torgersen, & Fox, 2008; Labov et al., 2006; Torgersen& Kerswill, 2004). Ideally, interpretation of children’sformant frequency data should take into considerationregional formant specifications at a particular time inhistory. Obviously, this most rigorous condition is noteasy to meet given the lack of detailed acoustic studiesthat compare regionally defined children’s and adults’speech samples collected at a given stage of a systemicvowel shift. Yet, even a basic knowledge of potential ef-fects of regional variation on acoustic characteristics ofvowels produced by children may prove to be helpful ininterpreting developmental data across English-speakingterritories. The extent to which children acquire dialectalvowel characteristics from the input provided to them byadults is a rich area for future research, of which foun-dation is laid out in the present study.

MethodParticipants

Ninety-four children ages 8–12 years (M = 9.9, SD =1.4) and 93 adults aged 51–65 years (M = 57.8, SD = 4.5)participated in the study. All participants were born,were raised, and have spent most of their lives in one ofthree geographic regions in the United States: westernNorth Carolina (the Cullowhee area), central Ohio (theColumbus area), and southeasternWisconsin (Madisonand areas east). These locations were selected becauseAmerican English spoken in each area represents a dis-tinct regional variety. In particular, vowel systems inthese three dialects exhibit substantial differences inboth vowel dispersion patterns and their dynamic formantmovements. The southern dialect in the Appalachianregion of western North Carolina is affected by sets ofchanges called the Southern Shift; the Midland dialect(the central Ohio variety) is regarded as not affected byany chain-like vowel shift found (Durian, 2010); and thenorthern variety spoken in southeasternWisconsin showsfeatures of another shift termed the Northern Cities Shift(NCS). More details about these regional varieties canbe found in Labov et al. (2006).

In terms of speaker gender, for females, there were16 girls and 16 women in each dialect group, making upa total of 96 females. For males, there were 16 boys and16 men in North Carolina, 15 boys and 13 men in Ohio,and 15 boys and 16 men inWisconsin, making up a totalof 91males. The participants were recruited using flyers,bulletin board postings, e-mail messages, and word ofmouth. Each participant spoke the local dialect as veri-fied by the research team, and none reported any speechdisorders or wore corrective devices. The recordings took

place in the years 2006–2008. The participants were paidfor their efforts.

Speech MaterialThe following 13 American English vowels were se-

lected: /i, I, e, e, æ, A, �, o, u,O, oI, aI, aO/. Each vowel wasproduced inh_d context in citation formusing the promptsheed, hid, heyd, head, had, hod, hawed, hoed, who’d, hood,hoyd, hide, howed. Each participant produced three repe-titions of each token for a total of 7,293 tokens used in theacoustic analysis (13 vowels × 3 repetitions × 187 speak-ers). These tokens, produced in isolation, provided not onlya commondatabase for all speakers but also auniformpre-sentation style. The assumption is that if the regionaldialect features are present in the most conservativeforms of vowels—that is, their citation forms—theymaysurface even more in everyday (spontaneous) speech.

ProcedurePrinted h_d prompts were presented to each partic-

ipant on a computer monitor, one at a time. A customMATLAB program was used to control the experimentand the recordings. In preparation for the experimentaltask, three different word lists were created as inputs tothe MATLAB program, in which each h_d token was re-peated three times. In each list, the tokens appeared in apseudorandom order in which there were no consecutivepresentations of the same item. Also, care was taken notto include adjacent items bearing potential for genera-tion of a false contrast such as in the case of “hod” and“hawed” which, in some dialects, have merged into onevowel category. No fillers were included. The word listswere counterbalanced across the participants within eachgroup. As alreadymentioned, each item from the list ap-peared as an individual prompt on the computer mon-itor. In six cases, however, additional information in theformof a rhymingwordwasdisplayedbeneath theprompt,as it was felt that speakers might encounter difficultiesin reading (i.e., understanding the expected phonetic formof certain nonce items). These includedheyd (rhymeswith“made”), hoyd (rhymes with “Lloyd” and “void”), hod(rhymeswith “odd”),who’d (rhymeswith “mood”),howed(rhymes with “cowed”), and hawed (rhymes with “sawed”).

The participant was seated facing a computer mon-itor and spoke each token into a head-mounted ShureSM10A dynamic microphone, positioned at a distance ofabout 1.5 in. from the speaker ’s lips. The experimenterused a separate computer monitor and keyboard/mouseand either accepted and saved the speaker’s production(which occurredmost of the time) or asked for a repetitionin case of any obvious mispronunciations (such as [haId]for “hid”) or poor-quality recordings. To familiarize thespeaker with the interface and the recording procedure, a


10-item practice was presented prior to the actual exper-iment. During the practice, the experimenter adjustedthe sound recording levels to the voice of an individualspeaker and established an allotted time for presenta-tion and production of each item. For most participants,the selected time slotwas 3 s. On occasion, slow speakersrequired 4 s in order to read and produce an item. Addi-tional repetitions were collected from the speaker if thesound level was either too soft or too loud (which was in-dicatedby color codingof the speaker’swaveformdisplayedon the screen immediately following theproduction) and incases such as “false” or “late” starts, “slips of the tongue,”laughing, coughing, sneezing, and so forth. The same pro-cedures were followed with both children and adults. Theduration of the task ranged from 15 to 20 min. Childrendid not encounter difficultieswith the task, partly becausethey were all fluent readers (including the 8-year-olds).This requirementwas included in theadvertisement of thestudy because the same childrenwere also to participatein a second experiment that involved reading fluently aset of 120 sentences with varying main sentence stress.

The tokenswere recorded anddigitized at a 44.1-kHzsampling rate directly onto a hard disc drive. The testingtook place at the university facilities in three locations:Western Carolina University, The Ohio State University,and University of Wisconsin—Madison. At the universi-ties in Ohio and Wisconsin, recordings took place in asound-attenuating booth. At Western Carolina Univer-sity, participants were recorded in a quiet room desig-nated for the experiment.

Acoustic MeasurementsPrior to acoustic analysis, the tokens were digitally

filtered and downsampled to 11.025 kHz. Spectral mea-surements included the frequencies of F1 and F2. Ameasure of formant movement termed trajectory lengthwas calculated from theF1andF2values sampled atmul-tiple time points in the course of the vowel’s duration.

Formant frequencies. F1 and F2 frequencies weremeasured over the course of the vowel’s duration at fiveequidistant temporal locations corresponding to the 20%–35%–50%–65%–80% point in the vowel. Vowel onsets andoffsets were located by hand, primarily on the basis of awaveform display with segmentation decisions checkedagainst a spectrogram. The 20% and 80% points wereused as the first and final spectral measurement loca-tions to eliminate the immediate contextual effects onvowel transitionsand to examine the vowel-inherent spec-tral change relatively unaffected by consonantal context.A 25-ms Hanning window was centered at each temporallocation. F1 andF2 values (based on 14-pole linear predic-tive coding [LPC] analysis) were extracted automaticallyusing a custom MATLAB program that displayed thesevalues along with the fast-Fourier transform (FFT) andLPC spectra and a wideband spectrogram of the vowel. If

needed, the formant values were verified using smoothedFFT spectra and wideband spectrograms with formanttracking (in the TF32 software program; Milenkovic,2003). A reliability check was performed on all tokens bytwo researchers, and any errors in formant estimationin LPC analysis were then hand corrected.

Trajectory length (TL). TL represents a measure offormantmovement that tracksmore closely formant fre-quency change over the course of vowel’s duration (seeFox & Jacewicz, 2009, for details). This measure utilizesthe five equidistant measurement points in a vowel(20%–35%–50%–65%–80%) to calculate the total tra-jectory change. The TL is a sum of the lengths of thefour separate vowel sections between the 20% and 80%point, where one vowel section length (VSL) is

VSLn ¼ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiðF1n � F1nþ1Þ2 þ ðF2n � F2nþ1Þ2

q: ð1Þ

The assumption is that a longer TL reflects a greateramount of formant movement in a vowel, indicatinggreater diphthongization. Here, the “length” of the for-mant trajectory, measured in Hz, indicates the amountof frequency change only and has no temporal compo-nent, per se. As it will become apparent in later sectionsof the paper, a vowel can still be considered “monoph-thongal,” having TL values up to about 420Hz, and in atrue diphthong such as /oI/, TL values can well exceed1000 Hz. In general, TLs of “diphthongal” vowels areexpected to be longer than 620Hz, and “diphthongized”vowels will fall into the 420–620 Hz range, based onaverage values in the present data.

Vowelduration.Measurements of voweldurationwereused as input for the automated measurement of formantfrequencies described above. To measure vowel duration,vowel onsets and offsets were located by hand, primarilyon the basis of a waveform display with segmentationdecisions checked against a spectrogram. The location ofthe vowel onsetwas defined as the onset of periodicity inthe waveform. Vowel offset was defined as that point atwhich the amplitude of thewaveformdropped significantly(to near zero), signaling the closure of /d/. Two additionalcues were used to verify the location of the stop closureonset: the lack of high-frequency energy (Pickett, 1999)and a relatively sinusoidal waveform, which is low in am-plitude and shows only slow variations (Olive, Greenwood,&Coleman, 1993). All segmentation decisionswere laterchecked and corrected during a reliability check.

ResultsVowel Dispersion in the Acoustic Space

Figures 1, 2, and 3 display relative positions of all13 vowels in the F1 × F2 plane, alongwith their dynamicformant patterns, produced by North Carolina (NC),Ohio (OH), andWisconsin (WI) participants, respectively.


The vowels are plotted following the sociolinguistic /sociophonetic tradition, in which the axes show F1 andF2 values in descending order. The vowels produced bychildren (boys and girls) are shown with reference toadults (males and females), who represent typical dialect-specific features of each regional variety. The displays arescaled to capture the systemic relations among vowelswithin each dialect. Given this purpose, the formant fre-quency values (in Hz) are not normalized, and each plotis scaled appropriately for each age and gender groupto render a comparable display.1 Specifically, the same

scaling is used for all children’s vowels, a common scal-ing is used for vowels produced by women, and anothercommon scaling is used for men’s plots. Each vowel sym-bol is placed next to the 80% temporal measurementpoint in the vowel, indicating the direction of formantmovement.

The vowels produced by NC adults in Figure 1 showthe characteristic positions of the Southern Shift: theproximity and considerable overlap of the /i, e, I, e / set,the raised and fronted /æ/, very fronted /u/ and /o/ (rela-tive to the onset of the diphthong /oI/), monophthongalversion of /aI/, and distinct relative positions of /A / and/� /. These characteristics can be found in bothmales andfemales. Comparedwith adults, children’s vowel systemsreflect considerable reorganization, which are not in theexpected direction of the Southern Shift. In particular,there is a separation of /i/ from /e, I, e/ and only a partialoverlap of the latter, especially in boys. The vowel /æ/

Figure 1. Mean relative positions of 13 vowels in h_d context and their formant movement (Formant 1 and Formant 2) measured at five equidistanttime points (20%–35%–50%–65%–80%) over the course of a vowel’s duration. Vowels are produced by speakers of the Southern dialect varietyof American English spoken in western North Carolina (NC): boys (n = 16), girls (n = 16), adult males (n = 16), and adult females (n = 16).Each vowel symbol is placed close to the 80% point in a vowel, indicating the direction of formant movement.

1Normalization procedures such as that developed by Lobanov (1971) aregenerally used to eliminate variation in the acoustic characteristicsbetween speakers related to vocal tract length. However, this procedureeliminates any direct correspondence with the measured formant valuesin Hz. Given that we needed to compare our results with those in theliterature—which are overwhelmingly described using non-normalizedHz values—we decided to use the Hz values for further considerationsand analyses of the dynamic formant movement.


undergoes lowering and backing, the monophthongal/aI/ becomes diphthongized (more in girls than in boys),and the vowel /� / changes both the pattern and directionof its formant movement. The diphthongs /oI/ and /aO/showacomparatively greateramount of frequency change.These changes in the vowel system indicate that, in gen-eral, the Southern Shift is gradually receding in this di-alect area. However, despite the differences, featuresof the southern dialect are clearly present in children’svowel system, including the very fronted /u/ and /o/, theproximity and partial overlap of /e, I, e /, and the distinctcharacter of the diphthongal /aI/, which, as we see below,does not display as great an amount of formant changeas in the OH and WI variants, at least not when pro-duced by boys.

The OH vowel system in adults (see Figure 2) pre-sents a different set of dialect-specific features. The vowels/I, e, æ/ are more centralized, are more clearly separated

from one another, and do not overlap with /e/, as was thecase in NC adults. The vowels /u/ and /o/ are fronted (al-though to a lesser extent than NC variants), and /A / and/�/ are close to each other, although they still representtwo distinct vowel categories. The vowels /aI, oI/ are fulldiphthongs andhavea greater amount of formant changethanNCvariants. As can be seen in Figure 2, these vowelcharacteristics are generally maintained in children. Thetwo innovations introduced by children include reductionof spectral change (i.e., greater monophthongization) of/I, e, æ/ along with the lowering of /æ/ and a correspond-ingmerger of /A / and /�/ into one vowel category. This lowback merger is prevalent in the productions of currentyoung adults and children who grew up in central Ohio(Thomas, 2001, p. 94; Labov et al., 2006, pp. 263–271).

Finally, vowels produced by WI adults display yet athird set of dialect-specific features. As Figure 3 shows,the vowels /e, æ/ are in close proximity. The greater

Figure 2. Mean relative positions of 13 vowels produced by speakers of the Midland dialect variety of American English spoken in centralOhio: boys (n = 15), girls (n = 16), adult males (n = 13), and adult females (n = 16). Each vowel symbol is placed close to the 80% point in a vowel,indicating the direction of formant movement.


formant movement in /æ/ indicates Northern breaking(see Labov et al., 2006, chapter 13), a characteristic markof English affected by the Northern Cities Shift. The WIvariant of /A / is positioned lower compared with NC andOH variants. Furthermore, both /u/ and /o/ are far backvowels, which is in sharp contrast with the fronted var-iants in NC and OH. As can be seen, WI children producemoremonophthongal versions of /I, e/ anda slightly raised/A /. All other dialect features—including the Northernbreaking in /æ/ and the back variants of /u, o/—remainas in the adults’ system.

In summary, the current data show considerablepresence of dialect-specific features in children’s produc-tions. Avisual inspection of the vowel system in each di-alect allows us to detect a remarkable correspondencebetween the systemic relations among vowels in the pro-ductions of adults and children. However, acoustic char-acteristics can also be found in children’s vowels that are

absent in adults. These new features may be related tochildren’s participation in the process of language (orsound) change in their respective regional varieties.Weexpand on these points in theGeneral Discussion. Priorto this, in the next section, we examine formant move-ment in vowels to determinewhether and to what extenta dialect-specific pattern of dynamic vowel characteris-tics is present in the productions of children comparedwith those of adults.

Formant DynamicsAs seen in Figures 1–3, there is substantial varia-

tion in the formant dynamics of vowels in the regionalvarieties considered here. To gain a better understand-ing of the amount of spectral change over the course ofa vowel’s duration, we examined changes in TL. Becausethemain interest of the study was to assess the effects of

Figure 3. Mean relative positions of 13 vowels produced by speakers of the Northern Midwestern dialect variety of American English spokenin southeastern Wisconsin: boys (n = 15), girls (n = 16), adult males (n = 16), and adult females (n = 16). Each vowel symbol is placed close tothe 80% point in a vowel, indicating the direction of formant movement.


dialect, one-way analyses of variance (ANOVAs) were con-ducted for each individual vowel, and this was done sep-arately for each age and gender group. In these ANOVAs,dialect was the only between-subjects factor. Significantgender effects were expected because we chose to workwith non-normalized formant values. For all vowels pro-duced by adult female speakers, we expected their TLs tobe longer than those of males due to their shorter vocaltracts. The gender-related differences were expected tobe smaller in children because anatomical differencesbetween girls and boys at this prepubertal age are notas dramatic as those between adult females and males.By the same reasoning, we predicted generally longerTLs in children than in adults, although dialect-specificreduction of formant movement in children, at least forselected vowels, cannot be ruled out because of their par-ticipation in the process of sound change and systemicvowel shifts. We address this point later in this article.

Initial analyses confirmedour expectations, showing,on average, longer TLs for adult females than for adultmales (581 Hz and 394 Hz, respectively) and longer TLs

for children than for adults (666 Hz for girls and 617 Hzfor boys). We now turn to the results of the ANOVAs thatassessed the effects of dialect. In these analyses, the de-grees of freedom (dfs) for the F tests were Greenhouse–Geisser adjusted to address significant violations ofsphericity. We also report a measure of the effect size—partial eta squared (h2). Following the significance of themain effect, Scheffé’s multiple comparisons were usedas post hoc tests. If children acquire dialect-specific pat-terns of formant dynamics, we expect to find similar cross-dialectal differences in vowel formant patterns in adultsand in children.

Table 1 summarizes the statistical results for theeffects of dialect in adult males and females. Listed areMs (andSDs) for TLs in vowels produced byNC,OH, andWI speakers, significance (p value), effect size (h2), andthe nature of significant differences between the dialectsas revealed by the Scheffé procedure. As can be seen, theamount of spectral changewasnot significantly differentacross dialects for the three vowels /i, A, o/, for bothmalesand females, or for /u/ and /aO/ in males. The remaining

Table 1. Summary of statistical results from one-way analyses of variance (ANOVAs) for formant trajectory length (TL) for the effects ofdialect in adults.

Vowel Token GenderNC

M (SD)OH

M (SD)WI

M (SD) p :2Significant difference

(Scheffé)

/i/ heed M 170 (51) 167 (70) 160 (41) .882 .006F 229 (77) 215 (60) 240 (94) .648 .019

/I/ hid M 398 (92) 276 (91) 359 (80) .002 .256 OH < NC; OH < WIF 647 (101) 461 (86) 577 (141) < .001 .336 OH < NC; OH < WI

/e/ heyd M 454 (112) 280 (60) 237 (82) < .001 .555 OH < NC; WI < NCF 661 (162) 384 (83) 339 (71) < .001 .631 OH < NC; WI < NC

/e/ head M 341 (102) 222 (67) 317 (61) .001 .297 OH < NC; OH < WIF 590 (155) 343 (71) 509 (180) < .001 .355 OH < NC; OH < WI

/æ/ had M 304 (107) 255 (105) 393 (89) .002 .255 OH < WIF 563 (208) 372 (111) 608 (142) < .001 .307 OH < NC; OH < WI

/A/ hod M 242 (95) 295 (100) 258 (78) .300 .056F 377 (128) 407 (165) 394 (52) .794 .010

/u/ who’d M 223 (102) 220 (126) 221 (48) .996 .000F 263 (125) 254 (83) 383 (112) .002 .240 OH < WI; NC < WI

/O/ hood M 242 (84) 342 (94) 487 (90) < .001 .591 NC < OH; NC < WI; OH < WIF 325 (135) 451 (111) 714 (149) < .001 .613 NC < OH; NC < WI; OH < WI

/o/ hoed M 307 (94) 260 (61) 255 (66) .121 .096F 444 (81) 425 (105) 367 (101) .070 .111

/�/ hawed M 271 (83) 293 (126) 391 (78) .002 .250 NC < WI; OH < WIF 378 (94) 423 (132) 492 (116) .026 .150 NC < WI

/aI/ hide M 229 (123) 777 (168) 837 (177) < .001 .772 NC < OH; NC < WIF 512 (330) 1,108 (140) 1,124 (178) < .001 .619 NC < OH; NC < WI

/�I/ hoyd M 841 (212) 1,138 (150) 1,134 (183) < .001 .383 NC < OH; NC < WIF 1,434 (245) 1,650 (180) 1,503 (254) .032 .142 NC < OH

/aO/ howed M 621 (133) 628 (110) 541 (90) .072 .118F 929 (219) 886 (126) 668 (111) < .001 .357 WI < OH; WI < NC

Note. Shown are Ms (SDs) in Hz, significance (p values), effect size (partial eta squared [:2]), and significant differences between the dialects obtainedfrom Scheffé’s pairwise comparisons. NC = North Carolina; OH = Ohio; WI = Wisconsin; M = male; F = female.


vowels showed significant variation in their TLs as afunction of dialect, pointing to several dialect-specificpecularities.

In particular, OH variants of /I, e, æ/ had the small-est amount of spectral change,NC /e/ andWI /� / were themost “diphthongal,” and each dialectal variant of /O/ dif-fered significantly one from another so that WI /O/ hadthe greatest amount of change, followed by OH and NC,respectively. As for the diphthongs, NC /aI/ was producedas a monophthong (which is in sharp contrast with bothOH andWI variants), andNC /oI/ had a lesser amount ofspectral change in comparison with the variants in bothOH (in both males and females) and in WI (in malesonly). WI /aO/ differed significantly from both OH andNC variants in females because its formant change wasgreater in F1 than in F2. WI males followed the samepattern of formant change in /aO/, although these dif-ferences did not reach significance.

How were these cross-dialectal patterns reflectedin children’s productions? Table 2 provides a summaryof the statistical results for the effects of dialect in boysand girls. The following results were consistent with theadults: (a) no significant differences for /i, A / in boys andgirls and no significant differences for /u, aO/ in boys and

(b) the same pattern of significant cross-dialectal differ-ences for /e/ in boys and girls, for /�/ in girls, and for /aI/ inboys. The results were partially consistent for /I, æ/: Twonew significant differences were found in children due tothe fact thatWI /I/ andNC /æ/ becamemonophthongizedin their productions. Also partially consistent were theresults for /O/; although children’s means still showedthe longest TLs for WI, followed by OH and NC, respec-tively, the differences between OH and WI boys and NCand OH girls were too small to reach significance.

The inconsistencies with the adults included (a) nosignificant differences for /e / in girls due to a considerablereduction of its formant movement (i.e., monophthongi-zation of /e /) in children; (b) no significant differencesfor /u/ in girls as a result of TL reduction in the WI var-iant; (c) significant differences betweenOH andNC boysand girls for /o/ that arose due to some reduction in TLs inOH children; (d) no significant differences for /�/ in boys;and (e) no significant differences for the diphthongs: /oI/in boys and girls, /aI/ and /aO/ in girls.

The question arises whether the differences betweenthe adults and children may have resulted, at least par-tially, fromdevelopmental factors rather than fromdialect-specific sound change over time. It is the case that most

Table 2. Summary of statistical results from one-way ANOVAs for formant TL for the effects of dialect in children.

Vowel Token GenderNC

M (SD)OH

M (SD)WI


(Scheffé)

/i/ heed M 303 (77) 308 (85) 279 (93) .601 .023F 316 (61) 316 (97) 337 (160) .824 .009

/I/ hid M 467 (158) 273 (60) 287 (84) < .001 .415 OH < NC; WI < NCF 477 (238) 277 (64) 263 (77) < .001 .314 OH < NC; WI < NC

/e/ heyd M 685 (141) 465 (156) 393 (129) < .001 .446 OH < NC; WI < NCF 736 (164) 503 (144) 473 (117) < .001 .418 OH < NC; WI < NC

/e/ head M 365 (144) 241 (63) 318 (86) .006 .207 OH < NCF 323 (140) 272 (74) 324 (68) .245 .061

/æ/ had M 346 (96) 303 (67) 565 (215) < .001 .415 OH < WI; NC < WIF 366 (107) 372 (103) 594 (144) < .001 .456 OH < WI; NC < WI

/A/ hod M 589 (194) 598 (111) 507 (111) .167 .078F 682 (181) 568 (154) 568 (186) .114 .092

/u/ who’d M 417 (132) 413 (133) 352 (120) .303 .053F 405 (130) 383 (118) 338 (92) .253 .059

/O/ hood M 358 (152) 512 (156) 587 (150) < .001 .294 NC < OH; NC < WIF 457 (117) 561 (154) 711 (130) < .001 .392 OH < WI; NC < WI

/o/ hoed M 467 (111) 367 (116) 430 (106) .047 .130 OH < NCF 515 (107) 399 (84) 452 (107) .008 .194 OH < NC

/�/ hawed M 503 (164) 552 (158) 605 (152) .216 .067F 518 (153) 565 (170) 687 (170) .017 .166 NC < WI

/aI/ hide M 829 (308) 1,201 (231) 1,192 (213) < .001 .333 NC < OH; NC < WIF 1,127 (319) 1,152 (233) 1,306 (218) .119 .090

/�I/ hoyd M 1,631 (433) 1,723 (328) 1,737 (227) .643 .020F 1,901 (232) 1,803 (241) 1,968 (294) .200 .069

/aO/ howed M 1,030 (188) 939 (205) 907 (161) .171 .077F 1,003 (146) 953 (166) 1,013 (189) .564 .025


studies on vowel development in typically developingchildren maintain that vowels are acquired relativelyearly, by 3–5 years of age (e.g., Lieberman, 1980; Pollock& Keiser, 1990; Stoel-Gammon & Beckett Herrington,1990; Templin, 1957; Winitz & Erwin, 1958). In terms offormant frequencies, it has been shown that children’svalues, despite being higher, show spectral patterningcomparable with that of adults. The higher formant fre-quencies in children are primarily a product of theirshorter supralaryngeal vocal tracts (Lieberman, 1980).In the present study, we found thatSDs in childrenwereslightly larger compared with those of adults, which in-dicated greater variation in their formant frequency val-ues. Thiswas somewhat expected, given that 8-year-oldsmay still have comparatively shorter vocal tracts than12-year-olds and that this age difference will producesome differences in the working vowel spaces of childrenin terms of absolute formant values (cf. Figures 2 and 3in Vorperian & Kent, 2007) but not in terms of relativepositions of the vowels in the vowel space. To examine ifthis assumption holds true for the present study, thegeneral means for the children’s data shown in Figures 1,2, and 3 were redistributed into the means for each yearof age, from 8 to12. The set of figures displaying thesevalues for each dialect is included in the Appendix.

It is now clear that developmental factors may comeinto play in the form of elevated F2 and F1 values for theyoungest children. For example, the vowels /i/ and /e/and the offset of /oI/ in the upper left corner of the vowelspace are fronted (i.e., have higher F2 values) in 8- and9-year-olds, and these high F2 values decrease with age.The back of the vowel space shows more variation, al-though generally higher F2 in /u/ and /o/ can be foundprimarily in younger children. However, despite the shiftsin F1 and F2, there is a robust, dialect-specific dispersionpattern of vowels in the vowel space of children at eachage, and this general pattern corresponds to the basicpatterning in the vowel space found in the adult speak-ers of each dialect.

Based on the analysis of formant movement (TL)presented above, it is clear that dialect-specific patternsof formant dynamics found in the adults are still presentin children’s productions. For some vowels, there is a re-markable correspondence in terms of both the amountof spectral change and trajectory shape. Across dialects,two general changes in children’s pronunciation can be de-tected that diverge fromadults’ productions: (a) reductionof formant movement (i.e., increased monophthongiza-tion) in selected vowels and (b) a more uniform pro-duction of all three diphthongs (i.e., /aI, aO, oI/), in whichthe dialectal differences seen in the adult speakers beginto disappear.

The present acoustic results provide evidence for re-gional distinctiveness of AmericanEnglish vowel systems.

Figures 4 and 5 illustrate several patterns for selectedvowels to substantiate this claim. As shown below, cross-dialectal positional differences are well maintained inchildren in spite of new vowel features such as signif-icant reductions in the amount of spectral change orchanges in formant trajectory shape. Furthermore, evenif the amount of formantmovement does not differ signif-icantly across dialects, children’s displays indicate theirknowledge of dialect-specific vowel positions in their re-spective vowel systems.

Considering the cross-dialectal variants of the vowel/e/ in Figure 4, we expect significant dialectal differencesin their TLs as listed in Tables 1 and 2: NC /e/ had signif-icantly greater formantmovement compared with eitherOH or WI, and the latter two did not differ significantlyfrom one another. This pattern can be seen clearly in Fig-ure 4, both in adults and in children. In addition, we alsofound that boys followed the same general cross-dialectdispersion as adult males (i.e., the NC variant is sepa-rated from both OH andWI, which are overlapping) andgirls followed the same general cross-dialect dispersionas adult females (i.e., all three variants tend to overlap).This gender-related observation should be interpretedwith caution, however, and further detailed studies areneeded to explore the role of gender in the acquisition ofselected vowels. The second vowel, /æ/, in the plots hasthree very different dialectal variants in adults: The tra-jectory shape of NC /æ/ signals what is known as theSouthern drawl or breaking, where the vowel “breaks”into two parts (Sledd, 1966); theWI variant showsNorth-ern breaking (Labov et al., 2006); and the OH /æ/ is mostmonophthongal, particularly in OH females. Children’splots indicate that their vowels still retain the cross-dialect positional differences despite a drastic reductionof formant movement in NC and OH variants and theapparent disappearance of Southern breaking in NCchildren.

The two remaining vowels in Figure 4, /A / and /u/,provide further evidence that children learn dialect-specific vowel positions. As listed in Tables 1 and 2, TLsfor /A / did not differ significantly as a function of dialect,either in adults or in children. However, the pattern ofcross-dialectal positional differences remained the samein each age group. The same was generally true for /u/,whose regional variants produced by adults and childrenalso showed remarkable consistencies in their trajectoryshapes.

Three further examples of cross-dialect variation inchildren’s vowels relative to adults are shown inFigure 5.First, the respective locations of cross-dialect variants of/e/ are well maintained in children despite considerablereduction in their formant movement in all three dia-lects, which is in line with the changes observed in /æ/in Figure 4. Second, the vowel /O/ exemplifies an inverse


scenario in which the cross-dialectal pattern of formantmovement found in adults ismaintained in children, butthere is some variation in the relative positions of OHand WI variants across age and gender groups. Finally,the cross-dialect renditions of /o/ clearly indicate thatchildren are aware of the dialect-specific pronunciationof the vowel that can be inferred from both the positionand formant trajectory shape of each dialect variant.

Vowel DurationGiven the nature of the experimental task (i.e.,

citation-form words produced in isolation), we did notexpect substantial effects of dialect, age, and gender onvowel duration. However, significant differences maystill show up for some vowels, which will help us detectwhether childrenalso learndialect-specific temporal vowelcharacteristics. We used a repeated-measures ANOVA toexamine the variation in vowel duration. In this ANOVA,vowel was included as a within-subject factor, and the

between-subjects factors were dialect, age, and gender.Not surprisingly, there was a significant main effect ofvowel,F(12, 2112) = 545.29, p < .001, h2 = .756, reflectingdifferences in the intrinsic vowel duration that is a wellknown property of vowels (e.g., Peterson&Lehiste, 1960).However, therewere onlymarginal effects for thebetween-subjects factors. The effect of gender was not significant.The effect of age was significant, but its effect size wasvery small, F(1, 176) = 4.49, p = .035, h2 = .025. The Msshowed that children produced slightly longer vowelsthan did adults (297 ms and 280 ms, respectively). Dia-lect was significant, but again, its effect size was small,F(2, 176) = 5.04, p = .007, h2 = .054. A subsequent ex-ploration of the effect of dialect using one-way ANOVAsand Scheffé’s comparisons as post hoc tests showed thatsignificant differences were found only for selected vow-els, as listed inTable 3. Interestingly, the pattern of cross-dialectal differences in vowel duration for the vowels/I, e,O/ is consistent for the adults and children. This find-ing suggests that children may also acquire temporal

Figure 4. Mean relative positions of /e, æ, A, u/ displayed cross-dialectally for children and adults. Data are redrawn from Figures 1, 2, and 3.


characteristics of vowels in their dialect.However, amoreappropriate design is needed to further explore the acqui-sition of vowel duration that should be tested in largerpassages of speech, including sentences and spontaneoustalks.

General DiscussionThis study examined relative positions and dynamic

formant patterns of vowels in three distinct regional varie-ties of American English as produced by 8- to 12-year-old

Table 3. Summary of statistical results from one-way ANOVAs for vowel duration for the effects of dialect in adultsand children.

Vowel TokenNC

M (SD)OH

M (SD)WI


(Scheffé)

Adults/I/ hid 254 (45) 205 (61) 185 (37) < .001 .278 OH < NC; WI < NC/e/ head 281 (51) 213 (59) 199 (42) < .001 .345 OH < NC; WI < NC/O/ hood 269 (49) 214 (66) 192 (40) < .001 .291 OH < NC; WI < NC

Children/I/ hid 256 (58) 224 (44) 193 (45) < .001 .220 OH < NC; WI < NC/e/ head 273 (49) 235 (44) 206 (53) < .001 .243 OH < NC; WI < NC/O/ hood 278 (59) 236 (44) 214 (59) < .001 .194 OH < NC; WI < NC/o/ hoed 339 (66) 321 (54) 296 (62) .021 .080 WI < NC

Figure 5. Mean relative positions of /e, O, o/ displayed cross-dialectally for children and adults. Data are redrawn from Figures 1, 2, and 3.


children and 51- to 65-year-old adults. Of interest waswhether the vowel systems of children retain dialect-specific features found in the vowel systems of adultsin terms of general dispersion pattern and the amountof vowel-inherent spectral change. The results demon-strate that regional characteristics are clearly presentin children’s vowels, even when elicited in their mostconservative citation forms (i.e., words produced in isola-tion). This indicates that, to a large extent, children ac-quire and reproduce the dialect features.

As already mentioned, all participants of the studywere born, were raised, and spent most of their lives intheir respective speech communities. From backgroundinformation collected at the time of testing, we foundthat they did not travel extensively out of state. Thus,most of the language input to both adults and childrenwas locally based, which no doubt included both strongregional features as well as new forms through interac-tions with newcomers to the area, mass media, or vari-ous forms of social networks. It needs to be pointed outthat the speech communities in both central Ohio andsoutheasternWisconsin are to some extent influenced bynew populations of students and academic staff associa-ted with two large research universities, The Ohio StateUniversity and the University of Wisconsin—Madison.In addition to being in close proximity toWesternCarolinaUniversity, thewesternNorthCarolina community is lo-cated close to theGreat SmokyMountainsNationalPark,which for years has been a popular tourist destinationduring the summer and autumn months and, more re-cently, experienced an increased in-migration of new res-idents from other states. It is, therefore, noteworthy thatthe adults in all three locations retained their regionalvowel characteristics and that the children were greatlyinfluenced by the dialect background of adults despitetheir increased exposure to nonlocal forms. This clearlyunderscores the role of local influences on linguistic be-havior of children, be it through input provided by adultssuch as parents and grandparents or by peers who speakthe local dialect (cf. Labov, 1991; Kerswill & Williams,2000; Roberts, 1997b, 2002; Stanford, 2008). This pointwas recently emphasized by Labov (2010b), who views theacquisition of cultural values as an important componentin mastering linguistic community patterns. He givesan example of high school students from the Midland(Columbus, OH) who do not accept linguistic norms oftheir peers from theNorthernCities Shift area (Cleveland,OH) because, for the Midland students, their Clevelandpeers are not models of linguistic influence.

This study is the first to show that learninga regionalvowel category involves learning the dialect-specific pat-terns of vowel-inherent spectral change. The present re-sults provide ample evidence that children do acquireregionally defined dynamic vowel characteristics. Themeasure of spectral change employed in this study, TL,

by nomeans provides an exhaustive characterization ofthe formant movement in time, as it lacks a true tem-poral component. In addition, it fails to account for thedirection of movement. Nonetheless, we found that afive-pointmeasurement system still can produce a goodestimate of the actual TL and a reasonable character-ization of the trajectory shape (see Fox & Jacewicz,2009, for evidence in favor of TL and a discussion of itslimitations). Comparing the TL measure with otherapproaches, it was shown in that study that the onset-to-offsetmeasurement used in the literature to calculatethe amount of spectral change, so-called vector length(e.g., Ferguson & Kewley-Port, 2002; Hillenbrand et al.,1995; Hillenbrand & Nearey, 1999), provides a reason-able measure of spectral change only when the diph-thong is moving in a relatively straight line in theacoustic vowel space. However, the vector length mea-sure severely underestimates the amount of formantchange in the case of more complex formant curves, asshown here.

When measuring vowel movement in the F1 × F2vowel space, the questionnaturally arises as tohowmanymeasurement points are needed to provide a reasonableestimate of the vowel’s position in the space as well aseither the length or the shape of its trajectory. A singlepoint (e.g., the 50% point) provides information aboutthe vowel’s location in the space, although it does notprovide any information about the amount of the spec-tral change. Two measurement points (e.g., the 20% and80% points) provide some information about spectralchange, but unless the movement is in a straight line,two points will not provide a good estimate of the lengthof the trajectory or its shape. Some studies haveused threepoints; ours uses five points, whereas others have used amore dense sampling (e.g., Van Son & Pols, 1992).

While using the TL measure derived from a five-point measurement, we were able to assess the amountof spectral change in a vowel as a function of speaker di-alect.We found that for some vowels, cross-dialect differ-ences in the amount of formantmovement found in adultscan be large, and similar variation was evident in chil-dren (compare the TL results for /e/ and /O/). This indi-cates that children do acquire dialect-specific patternsof formant dynamics when learning vowel categories intheir first language. Another findingwas that even if theamount of spectral change did not differ significantlyacross dialects, children’s productions showed similardialect-specific formant trajectory shapes as found inadults (e.g., in /u/ and /o/).

However, we also found a significant reduction offormantmovement in children’s /I, e, æ/ (except forNC /I/and WI /æ/) along with lowering of these vowels in theacoustic space. This new trend in children, which was ab-sent in adults, is an indication of children’s participation


in language change as argued in the sociolinguistic liter-ature (see Roberts, 2002, for a review). In particular, thepositional change of these three vowels is most likely re-lated to systemic changes (i.e., system-driven) inEnglishknown as vowel shifts. The present data support the op-eration of a key historical principle of vowel-chain shift-ing (Sievers, 1881), reformulatedmore recently byLabov(1994) as Principle II, which states that in chain shifts,lax nuclei fall along a nonperipheral track. Although thevariety spoken in central Ohio is not generally reportedto be participating in any vowel-chain shifts at present,we clearly see in children’s data a positional change inthese three vowels in accord with Principle II. A newfinding in the present study is that this positional changeis accompanied by a reduction of formant movement andthe vowels /I, e, æ/ becomingmoremonophthongal in chil-dren’s productions compared with those of adults.

Another set of new features in children found in thisstudy includes a systemic change in OH children’s vowelsystems called the low back merger, A > � (Labov, 1994;Thomas, 2001). This merger is becoming a standard fea-ture in CanadianEnglish and is spreading rapidly in theUnited States (Chambers, 1992; Labov et al., 2006). An-other systemic change known as æ > a backing can befound, particularly in OH and NC girls; æ > a backingseems to be related tomonophthongization and loweringof /æ/ in girls’ productions. This feature is still absentin WI children, most likely due to the extensive formantmovement in /æ/ that is common among WI speakers.Finally, we found that children’s diphthongs /oI, aI, aO/exhibit greater formantmovement thando those of adults,and dialect differences are gradually disappearing in chil-dren’s productions.

We need to emphasize that none of these new fea-tures in children’s vowel systems should be viewed as de-velopmental, which is evident from additional children’splots included in the Appendix. That is, whether we ex-amine the general Ms of 16 speakers across the ages8–12 years or the Ms of two speakers (or just a singlespeaker) broken down by each year of age, we find thesamegeneral patternsof dialect-specificpositional changesand dialect-specific patterns of formant dynamics. Neitherindividual variationnor a narrower breakdownbyage ob-scures these general patterns. The differences between8-year-olds and 12-year-olds are found in absolute fre-quency differences in F1 and F2, not in the patterningof the vowels within the vowel space. Moreover, we alsofound dialect-specific differences in vowel duration forselected vowels in children, which provide further evi-dence of the acquisition of dialect-specific vowel features.

In this study, we included bothmale and female par-ticipants in order to compare their dialect-specific vowelsystems and detect any potential gender-related differ-ences in vowel dispersion and formant dynamics.Overall,

only small differences were found for individual vowels,indicating that vowel systems of male and female speak-ers are generally similar in each dialect. As listed inTable 1, some differences in the amount of formant changewere found for five vowels in adults’ productions. In par-ticular, Scheffé’s comparisons showed that significantcross-dialectal differences in TLs varied slightly betweenmales and females. As for children’s productions, Table 2shows that such gender-related variation was found foronly three vowels. However, we can also detect some po-sitional differences between vowels produced by malesand those produced by females, particularly in the NCvowel system, which is undergoing greater reorganiza-tion than the OH andWI vowel systems. Tracing the po-sitional vowel changes in male and female vowel spacesin NC, it becomes apparent that both adult females andgirls manifest more advanced changes than do malespeakers, thus supporting the sociolinguistic position offemales as the leaders in linguistic change, especiallyunconscious ones or “changes from below” (Chambers,1995; Gauchat, 1905; Labov, 2001; Trudgill, 1974).

The findings of this work may prove to be helpful inbetter understanding and interpreting the developmentof vowel spaces in children. Most importantly, the studydirects attention to regional variation in vowel systemsof American English and the acquisition of regional fea-tures by children, including the dialect-specific patternof formant dynamics. This study documented regionalvariation in children’s vowel systems recorded in theyears 2006–2008, in a particular time in the history ofAmerican English. The present studywill be of interestto future investigators who will inquire into the devel-opment of vowel systems in children yet to be born. Fu-ture studies of this type will determine to what extentregional vowel systems have changed in time and whichdialect-specific features will be transmitted to youngergenerations.

AcknowledgmentsThis work was supported by National Institute on

Deafness and Other Communication Disorders ResearchGrant R01 DC006871.

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Appendix (p. 1 of 6). Mean first formant (F1) and second formant (F2)values for children in the study, redistributed for each year of age.

In Figures A1–A6, mean F1 and F2 values originally shown in Figures 1–3 as group means forboys and girls were redistributed for each year of age (from 8 to 12 years) to provide moredetails about the effects of dialect on vowel systems of younger and older children in each group.The plots show redistributed F1 and F2 values for North Carolina (NC) boys and girls, Ohio(OH) boys and girls, and Wisconsin (WI) boys and girls.

Figure A-1. Mean F1 and F2 values for OH boys.


Figure A-2. Mean F1 and F2 values for OH girls.



Figure A-3. Mean F1 and F2 values for NC boys.



Figure A-4. Mean F1 and F2 values for NC girls.



Figure A-5. Mean F1 and F2 values for WI boys.




Figure A-6. Mean F1 and F2 values for WI girls.


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