SUMMARY . ..... Actions: what evidence do we have of the acts of neuromotor learning that are supposed to be taking plac
The Role of Imitation in Learning to Pronounce
Piers Ruston Messum University College London April 2007
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Abstract Timing patterns and the qualities of speech sounds are two important aspects of pronunciation. It is generally believed that imitation from adult models is the mechanism by which a child replicates them. However, this account is unsatisfactory, both for theoretical reasons and because it leaves the developmental data difficult to explain.
I describe two alternative mechanisms. The first explains some timing patterns (vowel length changes, ‘rhythm’, etc) as emerging because a child’s production apparatus is small, immature and still being trained. As a result, both the aerodynamics of his speech and his style of speech breathing differ markedly from the adult model. Under their constraints the child modifies his segmental output in various ways which have effects on speech timing; but these effects are epiphenomenal rather than the result of being modelled directly.
The second mechanism accounts for how children learn to pronounce speech sounds. The common, but actually problematic, assumption is that a child does this by judging the similarity between his own and others’ output, and adjusting his production accordingly. Instead, I propose a role for the typical vocal interaction of early childhood where a mother reformulates (‘imitates’) her child’s output, reflecting back the linguistic intentions she imputes to him. From this expert, adult judgment of either similarity or functional equivalence, the child can determine correspondences between his production and adult output. This learning process is more complex than simple imitation but generates the most natural of forms for the underlying representation of speech sounds. As a result, some longstanding problems in speech can be resolved and an integrated developmental account of production and perception emerges.
Pronunciation is generally taught on the basis that imitation is the natural mechanism for its acquisition. If this is incorrect, then alternative methods should give better results than achieved at present.
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Table of Contents ABSTRACT..............................................................................................................................................................2 ABBREVIATIONS ..................................................................................................................................................8 ACKNOWLEDGMENTS .......................................................................................................................................9
1
INTRODUCTION ........................................................................................................................................11
PART 1 – THE REPLICATION OF PATTERNS OF TIMING
2
3
4
5
INTRODUCTION TO PART 1...................................................................................................................16 2.1
FOUR ‘TEMPORAL’ PHONETIC PHENOMENA ............................................................................................16
2.2
REPLICATION BY IMITATION (MODELLING) ............................................................................................18
2.3
OUTLINE OF PART 1 ...............................................................................................................................18
SPEECH BREATHING IN ADULTS AND CHILDREN ........................................................................20 3.1
SPEECH BREATHING IN ADULTS .............................................................................................................20
3.2
SPEECH BREATHING IN CHILDREN ..........................................................................................................21
3.3
STYLE OF ADULT SPEECH BREATHING ....................................................................................................24
3.4
STYLE OF CHILD SPEECH BREATHING .....................................................................................................27
3.5
THE NATURE OF A PULSATILE STYLE OF CHILD SPEECH BREATHING.......................................................28
3.5.1
Motor skill acquisition .....................................................................................................................28
3.5.2
The control of pulses ........................................................................................................................29
3.5.3
The magnitude of stress pulses.........................................................................................................30
PRE-FORTIS CLIPPING (PFC) ................................................................................................................31 4.1
INTRODUCTION ......................................................................................................................................31
4.2
A BREATH STREAM DYNAMIC (BSD) EXPLANATION FOR PFC ...............................................................32
4.3
PFC BEFORE FINAL FRICATIVES .............................................................................................................32
4.4
PFC BEFORE FINAL STOPS ......................................................................................................................34
4.5
EXTENSIONS AND EXCEPTIONS ..............................................................................................................36
4.6
SUMMARY .............................................................................................................................................37
RESPIRATORY SYSTEM INVOLVEMENT IN THE REALISATION OF STRESS-ACCENT ......38 5.1
ADULTS .................................................................................................................................................38
5.1.1
Evidence from observation...............................................................................................................39
5.1.2
Evidence from instrumental investigation of the production system ................................................39
3
5.1.3
Evidence from acoustic studies ........................................................................................................40
5.1.4
Summary...........................................................................................................................................41
5.2 5.2.1
When is stress-accent deployed? ......................................................................................................41
5.2.2
What style of speech breathing is used for stress? ...........................................................................42
5.2.3
Control and magnitude of stress pulses............................................................................................43
5.3 6
SUMMARY .............................................................................................................................................43
A BREATH STREAM DYNAMIC (BSD) ACCOUNT OF THE EMERGENCE OF THE WGmPh .45 6.1
FOOT LEVEL SHORTENING (FLS) ...........................................................................................................45
6.1.1
Appearance of rhythm and vowel reduction.....................................................................................45
6.1.2
Aerodynamic effects of syllable reduction........................................................................................46
6.1.3
Varieties of foot ................................................................................................................................47
6.1.4
The foot as a unit of production .......................................................................................................48
6.1.5
Timing ..............................................................................................................................................49
6.1.6
Learning ...........................................................................................................................................50
6.1.7
Summary...........................................................................................................................................50
6.2
VOWEL CHANGES UNDER THE INFLUENCE OF STRESS-ACCENT ..............................................................51
6.2.1
Appearance of tense and lax vowel classes ......................................................................................51
6.2.2
Aerodynamic vulnerabilities to stress-accent...................................................................................52
6.2.3
Vowel articulation: approximants and resonants ............................................................................53
6.2.4
Vowel adaptation to stress ...............................................................................................................55
6.2.5
Inconsistencies .................................................................................................................................61
6.2.6
Summary...........................................................................................................................................62
6.3
VOICE ONSET TIME, ASPIRATION ETC* ...................................................................................................63
6.4
FURTHER EFFECTS .................................................................................................................................65
6.4.1
P-centres ..........................................................................................................................................65
6.4.2
‘Syllable cut’ phonology...................................................................................................................65
6.4.3
Phonotactics.....................................................................................................................................65
6.4.4
Lengthening effects...........................................................................................................................66
6.4.5
Declination.......................................................................................................................................66
6.5 7
CHILDREN ..............................................................................................................................................41
SUMMARY .............................................................................................................................................67
PROBLEMS WITH AN IMITATIVE ACCOUNT OF ACQUISITION ................................................68 7.1
IMITATION AND OTHER MECHANISMS WHICH ACCOUNT FOR MATCHING BEHAVIOUR ............................68
7.1.1
Definitions ........................................................................................................................................68
7.1.2
Other aspects of ‘imitative’ performance.........................................................................................73
7.1.3
Imitation in children.........................................................................................................................74
7.1.4
Problems of interpretation ...............................................................................................................75
7.2
THE CONTROL AND VARIABILITY OF TIMING IN SPEECH .........................................................................75
7.3
ACQUIRING THE WEST GERMANIC PHENOMENA VIA IMITATION (MODELLING) OF THEIR TIMING ..........76
7.3.1
Goals: what underlies the child’s topographical learning?.............................................................76
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7.3.2
Actions: how does the child identify and use durational targets?....................................................77
7.3.3
Actions: what evidence do we have of the acts of neuromotor learning that are supposed to be
taking place? ..................................................................................................................................................78
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7.3.4
Results: is the child’s path consistent with an imitative process of acquisition? .............................78
7.3.5
Results: why is the final result in adults so variable? ......................................................................79
7.4
CHANGES IN PRODUCTION STRATEGIES..................................................................................................79
7.5
SUMMARY .............................................................................................................................................80
EVALUATING THE ACCOUNTS OF REPLICATION, AND FURTHER ISSUES ...........................81 8.1
EXPLAINING PHONETIC PATTERNS IN CHILDREN ....................................................................................81
8.1.1
Resilience of phenomena ..................................................................................................................81
8.1.2
Variable paths and variable results .................................................................................................81
8.1.3
Task complexity ................................................................................................................................82
8.1.4
Effect of power supply ......................................................................................................................82
8.1.5
Opinions among researchers ...........................................................................................................83
8.1.6
What would be evidence against the BSD account?.........................................................................83
8.2
EXPLAINING PHONETIC PATTERNS IN ADULTS ........................................................................................83
8.3
FUTURE WORK .......................................................................................................................................84
PART 2 – THE REPLICATION OF SPEECH SOUND QUALITIES
9
10
INTRODUCTION TO PART 2...................................................................................................................87 9.1
LEARNING TO SPEAK IN RURITANIA .......................................................................................................87
9.2
STRUCTURE OF PART 2...........................................................................................................................89
PRELIMINARIES .......................................................................................................................................91 10.1
NOTICING ..............................................................................................................................................91
10.2
AWARENESS OF SENSATION (AS) AND MEANINGFUL PERCEPTION (MP) ..............................................92
10.2.1
Different perspectives on perception ...........................................................................................92
10.2.2
Consequences of meaningful perception .....................................................................................97
10.3
TERMINOLOGY FOR PERCEPTION AND PRODUCTION .............................................................................100
10.4
PRODUCTION PRIOR TO THE TRANSITION TO WORDS ............................................................................102
10.4.1
Motor, auditory and proprioceptive (MAP) information...........................................................102
10.4.2
Inverse/forward models and passing control to the ear ............................................................103
10.4.3
Babbling ....................................................................................................................................105
10.4.4
Vocal motor schemes (VMS)......................................................................................................107
10.4.5
Protowords ................................................................................................................................107
10.5 11
SUMMARY ...........................................................................................................................................107
EARLY SPEECH PERCEPTION ............................................................................................................109 11.1
EARLY WORD RECOGNITION: ACQUAINTANCE .....................................................................................109
5
12
13
11.2
INFANT CATEGORISATION (EQUIVALENCE CLASSIFICATION) OF SOUNDS .............................................110
11.3
SUMMARY ...........................................................................................................................................113
LEARNING TO IMITATE .......................................................................................................................114 12.1
INTRODUCTION ....................................................................................................................................114
12.2
LEARNING WORDS BY IMITATION VS. LEARNING TO IMITATE SOUNDS .................................................115
12.3
PREVIOUS ACCOUNTS ..........................................................................................................................118
12.3.1
The child copies an acoustic model (mainstream accounts) .....................................................119
12.3.2
The child copies a gestural model .............................................................................................122
12.3.3
The child discovers the (speech) sounds he makes already being used linguistically by others123
12.3.4
The child discovers gestures he can already make being used linguistically by others ............126
12.3.5
Neural mechanisms ...................................................................................................................127
POTENTIAL PROBLEMS WITH SOME MODELS OF SPEECH SOUND DEVELOPMENT......129 13.1
INTRODUCTION ....................................................................................................................................129
13.2
CONCEPTS IN SOCIAL LEARNING ..........................................................................................................129
13.2.1
Distinguishing mimicry, pantomime and ‘purposive’ copying ..................................................130
13.2.2
Two types of ‘imitation’: how a model might be used to solve the correspondence problem when
signals are transparent.................................................................................................................................133 13.3
‘IMITATING’ SPEECH SOUNDS (1): PROBLEMS WITH LEARNING TO IMITATE BY MIMICRY .....................136
13.4
‘IMITATING’ SPEECH SOUNDS (2): PROBLEMS WITH RE-ENACTMENT BASED ON JUDGMENTS OF
SIMILARITY ........................................................................................................................................................139
13.4.1
Capturing extrinsic sound(s) .....................................................................................................141
13.4.2
Capturing intrinsic sound(s)......................................................................................................145
13.4.3
Comparing two auditory images* .............................................................................................150
13.5
13.5.1
Pattern of learning seen in practice* ........................................................................................151
13.5.2
How complex motor skills are learnt, other than by copying* ..................................................152
13.6 14
TWO FURTHER ARGUMENTS AGAINST COPYING ...................................................................................151
SUMMARY ...........................................................................................................................................152
LEARNING TO IMITATE: CREATING SOUND TO MOVEMENT CORRESPONDENCES.......156 14.1
THE ENTRY INTO SPEECH SOUNDS ........................................................................................................157
14.1.1
Reformulations ..........................................................................................................................158
14.1.2
Mirroring...................................................................................................................................159
14.1.3
Mirrored equivalence (ME).......................................................................................................162
14.1.4
Word adoption: parsing for production and word assembly.....................................................165
14.1.5
Development of sound qualities: reinforcement learning..........................................................169
14.2
SUPPORT FOR A ME ACCOUNT .............................................................................................................173
14.3
COMPARISON OF ME WITH OTHER ACCOUNTS .....................................................................................175
14.3.1
Comparison with copying accounts...........................................................................................176
14.3.2
Comparison with discovery accounts ........................................................................................176
14.4
SUMMARY ...........................................................................................................................................178
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15
SOME IMPLICATIONS OF A MIRRORED EQUIVALENCE (ME) ACCOUNT............................180 15.1
COMPARISON OF ME AND SBE: CATEGORISATION BEHAVIOUR...........................................................180
15.2
PUSHMI-PULLYU REPRESENTATIONS (PPR’S) ......................................................................................183
15.2.1
Description ................................................................................................................................183
15.2.2
Implications ...............................................................................................................................185
15.3
16
MODEL OF SPEECH DEVELOPMENT .......................................................................................................189
15.3.1
Description ................................................................................................................................189
15.3.2
Implications ...............................................................................................................................196
15.4
EARLY SPEECH PERCEPTION*...............................................................................................................197
15.5
SUMMARY ...........................................................................................................................................198
CONCLUSION ...........................................................................................................................................199 16.1
SUMMARY OF PART 1...........................................................................................................................199
16.2
SUMMARY OF PART 2...........................................................................................................................201
16.3
AFTERWORD: TEACHING PRONUNCIATION ...........................................................................................204
APPENDICES ......................................................................................................................................................206 APPENDIX A KNEIL (1972) “SUBGLOTTAL PRESSURES IN RELATION TO CHEST WALL MOVEMENT DURING SELECTED SAMPLES OF SPEECH”...................................................................207 APPENDIX B CALEB GATTEGNO (1911-1988)..........................................................................................212 APPENDIX C GATTEGNO (1985:6-21), EXTRACT FROM “THE LEARNING AND TEACHING OF FOREIGN LANGUAGES”.................................................................................................................................214
REFERENCES.....................................................................................................................................................221
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