StructurepreservationinintonationInvestigatingtheprosodyofinfant-directedspeechinEnglishandBengali

SameerudDowlaKhan,ReedCollegeMonday25February2013UniversityCollegeLondon

Outline

¡  QuestionsMotivationofstudy

¡  BackgroundIntonationalphonologyofEnglish,Bengali¡  DatacollectionExperiment,recordings,annotation

¡  ResultsIDSvs.non-IDS:similarities,differences¡  DiscussionProposedexplanationsforIDSdifferences

¡  ConclusionsSummary,upcomingextensions

Questions

Infant-directedspeech(IDS)

¡  Infant-directedspeech(IDS)ormothereseischaracterizedasinvolving:l  Syntactically:shortersentenceswithsimplerstructure1,focusmovement2

l  Lexically:smallervocabulary,paraphrasing3

l  Phonetically:expansionofvowelspace4,stopVOTmanipulation5,distinctiveprosody

1O’Grady1997:2502Cristia20113Ferguson1964,O’Grady1997:2504Andruski&Kuhl1996,Burnhametal.2002,Cristia20115Sundberg&Lacerda1999,Sundberg2001

Infant-directedspeech(IDS)

¡  IDSprosodyistraditionallyanalyzedfromanacoustic-phoneticapproach1

l  Expansionofpitchrange

l  Raisingofpitchmaximuml  Exaggerationofcontours

¡  Typicallyseenasanon-phonologicalorevenparalinguistic2phenomenon

1Jacobsonetal.1983,Sternetal.1983,Fernald&Simon1984,Fernaldetal.1989,Fernald&Mazzie1991,Greiser&Kuhl1998,Masataka19992Jacobsonetal.1983,O’Grady1997:250

Infant-directedspeech(IDS)

Infant-directedspeech(IDS)

Basicquestions

¡  It’swell-establishedthatcross-linguistically,IDSprosodyinvolvesawiderpitchrange

¡  Butaretherecategoricalchangesbetweennon-IDSandIDSprosody?

¡ Whatlinguisticinformationmightbeconveyedbythechanges?

¡ Whatcouldbethepressuresmotivatingthesechanges?

Background

Intonationalphonology

¡  Tohelplookbeyondlg.-specificprosodicproperties,Ilookedattwolanguageswithtypologicallydivergentintonation:l  MainstreamAmericanEnglish

l  BangladeshiStandardBengali1

1ThevarietyillustratedinKhan2010

Intonationalphonology

¡  SharedfeaturesofEnglishandBengali:l  Pitchaccents1:tonesmarkingwordsl  Intonationphrases(IPs)2:tonally-markedunitsl  Boundarytones:tonesmarkingendsofIPs

¡  Language-specificfeatures:l  Inventoryofintonationaltonesl  Whatisconveyedbyspecifictonesequences

1Thesearepostlexicalpitchaccents,unlikethelexicalpitchaccentsofJapanese,Swedish,etc.,inthattheirpresenceandshapearenotpropertiesoftheword.2These“phrases”areprosodicunits,onlyindirectlyconnectedtosyntacticunits.

English:pitchaccents

¡  Pitchaccentsoccuronthestressedsyllableofprominentwords

l  Partialinventory:Default Non-default(rising)H*(high) L+H*(earlyrise)1

L*(low) L*+H(laterise)

l  Choiceisrelatedtoattitude2,focusstatus2,andtonalenvironment3

1ManyresearchersconsiderH*andL+H*tobevariantsofthesamepitchaccent.2Beckman&Hirschberg19903Dainora2002,2006

English:intonationphrases

¡  Boundarytonesoccurattheendsofintonationphrases(IPs)l  Partialinventory:

¡  L-L%(low)¡ H-H%(high)

l  Choiceisrelatedtosentencetype,speakerconfidence,finality1

1Beckman&Hirschberg1990

Bengali:pitchaccents

¡  Pitchaccentsoccurontheinitialsyllableofnearlyallwordsl  Partialinventory:

Default Non-default(f-marked)L*(low) fH*(extrahigh) L*+fH(risetoextrahigh)

l  Choiceisrelatedtospeakerattitude1,focusstatus/type2,andtonalenvironment

1H*markssarcasmorsurprise,L*otherwise(Khan2008,2013toappear)2Thechoiceoff-markedtonelargelydependsonfocustype(Khan2008,2013toappear)

Bengali:boundarytones

¡  BoundarytonesmarktheendsofIPsl  Partialinventory:

L-initial H-initialL%(lowfall) H%(highrise)LH%(lowrise) HL%(highfall) HLH%(highfall-rise)

l  Choiceisrelatedtosentencetype,informationstructure,finality1

1Khan2008,2013toappear

Bengali:boundarytones

¡  BoundarytonesmarktheendsofIPsl  Partialinventory:

L-initial H-initialL%(lowfall) H%(highrise)LH%(lowrise) HL%(highfall) HLH%(highfall-rise)

l  Choiceisrelatedtosentencetype,informationstructure,finality1

Bothcanserveastopicalizers

1Khan2008,2013toappear

Bengali:boundarytones

¡  BoundarytonesmarktheendsofIPsl  Partialinventory:

L-initial H-initialL%(lowfall) H%(highrise)LH%(lowrise) HL%(highfall) HLH%(highfall-rise)

l  Choiceisrelatedtosentencetype,informationstructure,finality1

Bothcanserveascontinuationrises

1Khan2008,2013toappear

Variablephrasing

¡  Prosodicphrasinginbothlanguagesisaffectedby:l  Syntacticstructure,e.g.disambiguation

[old[menandwomen]]<IP>[[oldmen]<IP>andwomen]<IP>

l  Informationstructure,e.g.focusIsawyourmotherreadingthemenu.<IP>IsawYOURMOTHER<IP>readingthemenu.<IP>l  Otherfactors,e.g.speechrate

Datacollection

Design:subjects

¡  19subjectsl  9speakersofEnglish(5M,4F)l  10speakersofBengali(5M,5F)

¡  Allwereparentsofyoungchildren¡  AllresideintheLosAngelesarea

Design:materials

¡  Recordedreadingsofthe“NorthWindandSun”fablel  SuitableforadultspeechandIDSl  Similarsemantics/pragmaticsacrosslanguagesl  Consistentsemantics,morphosyntax,segmentalphonologyacrossconditions

Design:conditions

¡  Twoconditionsl  Defaultreading(non-IDS):“Readatacomfortablepace.”

l  Simulatedinfant-directedreading(IDS):“Readasthoughyouspeakingtoaninfant.”¡ Sametext,illustratedwithchildlikedrawings¡ Stuffedanimalsarrangedaroundspeaker

Experiment:annotation

¡  Englishannotationl  Segmental:orthographyl  Prosodic:tonelabelsfromMAE_ToBI1

¡  Bengaliannotationl  Segmental:phonemicromanizationl  Prosodic:tonelabelsfromB-ToBI2

1Beckmanetal.20052Khan2008,2013toappear

Analysis

¡  Acoustic-phoneticmeasurementsl  Pitchrange

¡  Categorical/phonologicalmeasurementsl  Inventoryoftonesl  Numberofpitchaccentsl  NumberofIPsl  Numberofeachtypeofpitchaccentsl  Numberofeachtypeofboundarytones

Results

Previewofresults

¡ What’sthesameacrossconditions:l  Foreachlg.,IDSandnon-IDScanbothbeanalyzedusingthesameprosodicmodel

¡ Whatdiffersacrossconditions:l  IDShaswiderpitchrange(highermax)l  IDShasmoreIPsl  SometonesaremorefrequentinIDSl  IDShasmoreoverallcontourcomplexity

Structurepreservation

¡  IDSprosodyusesthesametonalinventoryandgrammarasnon-IDSprosodyl  Noneedtoproposenew(allo)tonesforIDSl  Samerelationsbetweentonesequenceandintonational“meanings”

Structurepreservation

¡  Intonationalstructurepreservationl  cf.phonemicstructurepreservation,inwhichaphonologicalprocessresultsinasoundalreadyfoundinthephonemeinventory

l  German/d/ à [–voi] / ___]word¡  /t/ alreadyfoundininventory

l  Bengali/LH%/ à [HLH%] / [...___...]IDS¡  /HLH%/alreadyfoundininventory

Pitchrange

¡  AllBengalispeakersraisedthef0maxinIDS

¡  f0minnotconsistentlylowered

¡  SamepatternseeninEnglish

¡  Followsfrompreviousstudies

¡  “Authentic”IDS

IDS non-IDS

meanf090%f0range

10%f0range

PreviewofEnglish-specificresults

¡  EnglishIDSinvolves:l  Increaseinrisingpitchaccentsl  IncreaseinIPs

English:pitchaccents

¡  Onaverage,speakersincreasedthenumberandproportionofrisingpitchaccentsinIDSl  3.9%increaseinL*+Hproportion[p=0.02]l  7.5%increaseinL+H*proportion[p=0.01]

byspkr.

English:intonationphrases

¡  Onaverage,Englishspeakersproduced33.3%(=3.44)moreIPsinIDS[p<0.01]

byspkr.

PreviewofBengali-specificresults

¡  BengaliIDSinvolves:l  Increaseinf-markedpitchaccentsl  IncreaseinIPsl  IncreaseinHL%andHLH%boundarytones

Bengali:pitchaccents

¡  f-markedpitchaccentuseishigherinIDSforallbutonespeakerl  fH*l  L*+fH

byspkr.

fH*,L*+fHinnon-IDS

fH*,L*+fHinIDS

Bengali:intonationphrases

¡  Onaverage,Bengalispeakersproduced49.0%(=8.97)moreIPsinIDS[p<0.01]

byspkr.

Bengali:boundarytones

¡  TheincreaseinIPscanbelargelyattributedtoincreasesinthoseendingin:l HL%(highfalling)l HLH%(highfalling-rising)

byspkr.

HL%,HLH%inIDS

HL%,HLH%innon-IDS

Summaryofresults

¡  TrueforIDSinbothlanguages:l  Morenon-defaultpitchaccents

¡ Despitelackofincreaseindefaultpitchaccents

l  MoreIPs¡ Certainboundarytonesweremorecommon

¡  So,whydoweseethesemodifications?

Discussion

Why:pitchaccentpatterns

¡ WhydoesIDSinvolveanincreaseinnon-defaultaccents?l  EnglishrisingL*+HandL+H*l  Bengalif-markedfH*andL*+fH

¡  ThesetonescanmarkfocusedelementsèGreateruseoffocusprosodyinIDS1

1IDScanalsoinvolvegreateruseofsyntacticmovementtoconveyfocus(Cristia2011).

Why:phrasingpatterns

¡ WhydoesIDSinvolvemoreIPs?l  IPbreakshelpdisambiguatesyntaxl  Boundarytonesconveyinformationstructure

¡ BengaliHL%canmarktopicalization

èMoremarkingofsyntactic/informationstructureinIDS

Why:contourpreference

¡  TherecouldbeotherreasonswhyrisingpitchaccentsandH-initialboundarytonesaremorecommoninIDSl  Preferenceformorepitchvariation,to“keepthingsinteresting”fortheinfant1

l  PreferencefortonesinvolvingHasinfantspreferhigherpitch2

1Fernald1991,Werker&McLeod19892Kearsley1973,Fernald&Kuhl1981

Why:contourpreference

¡  Butonlytoneswithwell-formedcomplexandhighcounterpartscanundergothissubstitution

¡  IDSbalancesgrabbing/keepinginfant’sattentionwithstructurepreservation

Conclusions

Returningtothequestions

¡  Aretherecategoricalchangesbetweennon-IDSandIDSprosody?l  Moresubstitutionofdefaultpitchaccentswithnon-defaultpitchaccents

l  HigherlikelihoodtoaddIPbreaksl  Moresubstitutionoflower/simplertoneswithhigher/morecomplextones

l  But...thebasicprosodicsystemisthesame

Yes(but...)

Returningtothequestions

¡ Whatlinguisticinformationmightbeconveyedbythechanges?l  GreateruseofIPbreakscandisambiguatesyntacticstructure

l  GreateruseofIPbreaksandnon-defaultpitchaccentscanhighlighttopic,focus

Returningtothequestions

¡ Whatcouldbethepressuresmotivatingthesechanges?l  Pressurestowardsgreatercomplexity:desiretoattractinfant’sattention,desiretoclarifycomplexstructures

l  Pressureagainstgreatercomplexity:intonationalstructurepreservation

Workinprogress

¡ Moredataontheway!l  SecondtranscribercurrentlyannotatingEnglishl  SecondtranscriberhasalreadyannotatedBengali,dataiscurrentlybeinganalyzed

Workinprogress

¡ Moreprincipledwayoflookingattheconnectionbetweenphonologicalchangesandsyntax/informationstructurel  e.g.isprobabilityofIPbreakhigheratlargesyntacticphrasebreaks?

¡  Agreatareaforcollaborationacrosslinguisticsubfields!

Thankyou!

SpecialthankstomycollaboratorKristineM.Yu,aswellastoJaimePannaRoemer,MeghaSundara,theReedCollegeLinguisticsDepartment,theexperimentalsubjects,andtheaudiencehereatUCL!