The Shifty Vowels of African American English Youth: A Longitudinal Study

Mary Kohn UNC Chapel Hill Charlie Farrington University of Oregon LSA 2013, January 4

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“Adolescents  lead  the  en/re  age  spectrum  in  sound  change  and  in  the  general  use  of  vernacular  variables,  and  this  lead  is  a:ributed  to  adolescents’  engagement  in  construc/ng  iden//es  in  opposi/on  to  -­‐  or  at  least  independently  of  -­‐  their  elders”                        (Eckert  1997:  163)      

Adolescent Peaks

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Linguis/c  Lifecycles  

-  As linguists reject theories which identify acquisition as the primary site for innovation, the primary questions regarding sound change become:

Who Changes? When?

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Changes in Progress -  Labov (2001) hypothesizes that

sound change progresses within the individual as a logistic function from childhood through adolescence

Stable Vernacular Variation/ Age Grading -  Stable variation may show peaks

before retracting to earlier levels -  Commonly identified with

morphosyntactic variation Only longitudinal data with multiple time points can trace variable trajectories in real-time

Peak? Or Increments?

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-4 -2 0 2 4

0.0

0.2

0.4

0.6

0.8

1.0

time

change

The S-Curve of Linguistic Change

0 1 2 3 4 5 6

-1.0

-0.5

0.0

0.5

1.0

x

y

Age Grading

0 1 2 3 4 5 6

-1.0

-0.5

0.0

0.5

1.0

time

change

Age Grading

-­‐  Prominent  dip  in  1st  and  4th  grade,  most  children  peak  in  8th  or  10th  grade,  and  dip  post  high  school  (Frank  Porter  Graham)  

-­‐  Speakers  use  more  AAVE  features  during  adolescence  when  compared  to  adulthood  (Baugh  1996,  Rickford  &  McNair-­‐Knox  1994,  Cukor-­‐Avila  2002)  

 

Longitudinal African American Morphosyntactic development

Van  Hofwegen  and  Wolfram  2010  

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While longitudinal studies of morphosyntactic and segmental variation have been comprehensive, the longitudinal analysis of vowel change has been

…limited in duration -  Wagner (2008): 2 intervals, 1 year apart

…limited in subjects (case studies) -  Sankoff (2004): 2 speakers -  De Decker (2006): 4 Speakers

Panel studies for adolescents

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Until a comprehensive analysis is available from childhood to early

adulthood, the relationship between adolescent peaks/increments and sound change remains unknown.

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Longitudinal change and interaction between subsystems

1.  Do AAVS vowels have an adolescent peak similar to AAVE morphosyntactic features?

2.  Do changing regional vowels stabilize in high school following logistic increments?

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9  

Speakers  range  from  rigorous  par/cipa/on  in  the  African  American  Vowel  System  to  alignment  with  the  emerging  European  American  vowel  system  in  the  region  

BAT Raising/Fronting •  Part of AAVS for at least 100

years (Bailey & Thomas 1998) •  A cue to ethnicity in perception

tests (Thomas et al. 2010) •  Appeared as part of the SVS in

Raleigh, but is rapidly receding among European Americans (Dodsworth & Kohn 2012)

Does BAT Raising/Fronting show adolescent peaking?

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BOAT/BOOT fronting •  A well-documented sound change

across the South, evidence for African American participation in back vowel fronting is more recent (Fridland 2003)

•  Yet fronting may not be pervasive in African American communities in the region (Dodsworth and Kohn 2009)

•  Backed BOAT a cue to ethnicity in perception tests (Thomas et al. 2010)

Does back vowel fronting show logistic increments?

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•  1990: 88 African American children from 6-12 months (mean 8.1 months)

•  2011: 67 continue in study

•  71% below poverty level

•  Batteries of standardized and nonstandardized tests, including progressively collected language samples annually or bi-annually

Frank Porter Graham

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Methods •  Participants=20 children

–  Similar socioeconomic backgrounds

•  Recordings from: –  4th Grade (Age 9) –  8th Grade (Age 13) –  10th Grade (Age 15) –  Post High School (Age 20)

•  Recordings come from peer interactions, standardized tests, and sociolinguistic interviews.

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See Kohn & Farrington 2012

≈ 200 tokens of vowels for each speaker = 18,000

vowels /i/ BEET*  

/ai/ BITE/BIDE  

/æ/ BAT,  BAN  

/o/ BOAT,  BOAR  

/ɑ/ BOT  /ɔ/ BOUGHT  

/ɪ/ BIT  

/ei/ BAIT  /ɛ/ BET  

/u/ BOOT  /ʊ/ BOOK  

/ʌ/ BUT  

Hierarchical  Mixed  Model  Regressions  (Singer  &  Wille:  2003)  

Random  Effects  •  Speaker  •  Grade/Age  Fixed  Effects  •  Grade  •  Phonological  

environment  –  Following  for  BAT  and  BOAT  

–  Preceding  for  BOOT  •  Dura/on  •  Sex  •  Sex*Grade  

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•  Longitudinal  analysis  requires  special  treatment  “/me”  and  “speaker”    to  recognize  the  non-­‐independent  nature  of  within-­‐speaker  measures  across  /me  intervals  

•  Including  “grade”  as  a  fixed  and  random  effect  allows  for  iden/fica/on  of  group  trends  beyond  individual  trajectories  

•  Both  linear  and  quadra/c  models  were  assessed  

•  Best  models  selected  through  ANOVA  comparisons    

BAT  F1  and  F2:  Adolescent  Peak?  

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BAT  F1  Peak:  Highest  Median  value  

4th   8th   10th   Post-­‐High  School  256  1003  1035  1075  1085    

268  280  1025  1057  1062  1070  1078  

269  274  275  1001  1015  1058    

1061  1072  

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Increments  

17  

Speaker  256  lowers  BAT  across  adolescence  

Peaks  

18  

Speaker  1078  demonstrates  Age-­‐Graded  behavior  with  BAT  raising  

Stability,  Increments,  Peaks,  and  Troughs  

19  

Although  7/20  speakers  are  stable,  

Peaking  is  the  majority  pa:ern  

BAT  F1:  Best  Model  Quadra/c  Model  Random  Effects  •  Speaker  •  Grade  Fixed  Effects  •  Grade  (n.s.)  (-­‐.046)  •  Grade^2  (n.s.)  (.002)  •  Phonological  environment  

–  Labial***  (.26)  –  Velar**    (.07)  –  glo:al  (n.s.)  (-­‐.02)  –  None  (n.s.)  (-­‐.03)  

•  Dura/on*  (-­‐.32)  •  Sex  (n.s.)  (-­‐.022)  •  Sex*Grade**  (.02)  

20  

Women  and  Men  on  Different  Paths  

Males  and  Females  

21  

BAT  F2  Peak:  Most  Fronted  Median  value  

4th   8th   10th   Post-­‐High  School  256  280  1015  1025  1061  1085  

269  275  1035  1057  1062  1072  1075  1078  

268  274  1003  

1001  1058  1070  

22  

Increments  

23  

Peaks  

24  

25  

Stability,  Increments,  Peaks,  and  Troughs  

Increments  where  Post-­‐High  School  is  more  back  is  the  most  common  pa:ern  (9/20),  but  8th  grade  tends  to  peak    or  show  li:le  change  between  4th  and  8th  

BAT  F2:  Best  Model  Quadra/c  Model  Random  Effects  •  Speaker  •  Grade  Fixed  Effects  •  Grade  *  (.036)  •  Grade^2  **  (-­‐.002)  •  Phonological  environment  

–  Labial***(-­‐.12)  –  Glo:al***(.07)  –  Velar  (n.s.)(-­‐.009)  –  None  (n.s.)  (.09)  

•  Dura/on*  •  Sex  

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•  BAT F1 does not have significant group change, but does show an interaction between sex and grade – Majority of speakers have an 8th grade or 10th

grade peak – Women demonstrate wider distribution

•  BAT F2 shows significant backing, but this change is best represented by a curvilinear model which suggests peaking or plateaus around 8th grade

Observed Patterns

27  

BOAT  and  BOOT  F2:  Logis/c  Incrementa/on?  

28  

BOAT  F2  

29  

Peak:  Most  fronted  Median  value  

4th   8th   10th   Post-­‐High  School  268  275  1003  1058  1070  1085  

269  274  1057  1072  1075  

256  1001  1015  1061  1078  

280  1025  1035  1062  

•  Best  Sta/s/cal  Model  includes  a  random  effect  for  speaker,  and  a  quadra/c  random  effect  for  /me  

•  But  only  phonological  variables  are  significant  

•  Inter-­‐speaker  variance  <.1  

Stability  and  Peaks  

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14  of  the  20  speakers  demonstrate  stability  for  the  BOAT  class  F2  

Not  all  speakers  are  stable,  but  most  are  

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BOOT  F2  Peak:  Most  fronted  Median  value  

4th   8th   10th   Post-­‐High  School  268   275  

280  1003  1035  1057  1061  1075  

269  1001  1025  1070  1078  1085  

256  274  1015  1058  1062  

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BOOT  F2:  Best  Model  Quadra/c  Model  Random  Effects  •  Speaker  •  Grade  Fixed  Effects  •  Grade  (p=.10)  (.04)  •  Grade^2  (n.s.)  (-­‐.001)  •  Phonological  environment  

–  Labial***  (-­‐.6)  –  Velar***  (-­‐.39)  –  glo:al  ***  (-­‐.56)  

•  Dura/on*  (.02)  •  Sex  (n.s.)  (.07)  •  Sex*Grade  (p  =  .09)  (note:  two  outliers  removed  from  

graphic)  33  

Women  and  Men  on  Different  Paths  

Median  change  for  Women  and  Men  for  BOOT  

34  

•  BAT retraction is vigorous within the community, but it occurs in a curvilinear fashion –  No significant gender effect indicates that men

participate in this pattern as well •  BOAT fronting demonstrates little evidence for

change •  Evidence for gendered behavior BAT raising and

potentially BOOT fronting –  Men backing away from BOOT fronting –  Women raising BAT

Observations

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Conclusions  •  Do  vowels  follow  morphosyntac/c  pa:erns?  

– Not  always  –  BAT  backing  follows  morphosyntac/c  pa:erns  –  But  other  AAVS  vowels  remain  stable  (BOAT  F2)  or  show  gendered  behavior  (BAT  F1,  BOOT  F2),  possibly  indica/ng  that  mi/ga/ng  interac/ons  with  social  variables  influence  trajectories  of  change  

•  Do  vowels  peak  or  show  logis/c  pa:erns?  –  Change  is  not  linear  –  But  some  speakers  may  demonstrate  age-­‐grading  and  change,  peaking  but  not  returning  to  ini/al  levels  of  behavior  

36  

Conclusions  

•  Independent  trajectories  for  different  vowel  classes  may  support  the  hypothesis  that  back  and  front  vowel  systems  are  independent  of  each  other  in  Southern  American  varie/es  

•  Some  evidence  for  logis/c  pa:ern  of  sound  change,  but  peaking  pa:erns  also  emerge.    – Do  older  sound  changes  show  more  peaking/age-­‐grading?  

•  Evidence  for  independent  pa:erns  for  males  and  females  for  some  vowel  classes  

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Adolescent  Peak  

•  “Adolescents  lead  the  en/re  age  spectrum  in  sound  change  and  in  the  general  use  of  vernacular  variables”  

•  Although  this  might  be  true  for  some  vowels  for  some  speakers…  

•  Adolescent  peaking  is  not  the  only  way  in  which  sound  change  progresses  throughout  the  life  cycle  of  the  individual  

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Acknowledgements

National Science Foundation Grant BCS-0544744 BCS-0843865

Susan Zeisel for making this project possible, David Ethier for data collection, Walt Wolfram for offering insight, Erik Thomas for assistance throughout the process, Tyler Kendall and the Oregon LVC Lab, all of the NCLLP crew, especially Janneke Van Hofwegen and Jenn Renn for helping us navigate the data.

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42  

Stability,  Increments,  Peaks,  and  Troughs  By  Means  BAT  F2  

8th  grade  peak  is  the  majority  pa:ern  

BAT  F1  Variance  Components  

43  

BAT  F2  Variance  Components  

44  

BOAT  Variance  Components  

45  

BOOT  F2  Variance  components  

46  

Non-­‐  uniform/  gender  specific  development  of  the  vocal  tract  

Early  childhood  5-­‐10   Onset  of  

Puberty  10-­‐15   Physical  matura/on  15<  

•   sexual  dimorphism  in  low  and  mid  vowels  before  age  5  (Whiteside  2001)  •   Overall  decline  in  vowel  space  •   reduc/on  in  varia/on  Eguchi  and  Hirsh  (1969)    

 

•   15  yrs:    Significant  difference  in  pharynx  length  (Fitch  and  Giedd  1999).    •   Males:  Rapid  formant  descent  •   Females  :  shallow  descent  (Vorperian  and  Kent  1999)  •  Adult-­‐like  f3  achieved  

• Growth  of  oral  tract  is  proporAonal  (correlated  with  F1)  (Fant  1975)  • Growth  of  pharynx  non-­‐proporAonal  to  oral  tract  (correlated  with  F2)  (Fant  1975)  • Greatest  sex  differences  for  low  vowel  F1  (e.g.  Fant  1975,  Vorperian  and  Kent  1999).    

•   Female  f1  s/ll  not  adult-­‐like  (Whiteside  2001)  •     significant  difference  in  pharynx  length  by  age  15  (Fitch  and  Giedd  1999).    

Choice  of  normalizaMon  technique  

Lobanov    (1971)  •  Formant  extrinsic  •  Vowel  extrinsic  •  Top-­‐performing  when  compared  to  other  techniques  (Clopper  

2009,  Adank  et  al  2004)  •  Modified  for  the  sample  popula/on  vowels:  BEET,  BOAR,  BAT,  

BOT    

Fi  –  Grand  Mean  Fi  /  Standard  devia/on    

EffecMveness  of  NormalizaMon