1. Discourse Structure in Generation
Julia Hirschberg
CS 4706
12/6/2018

2. Today Models of Discourse Structure Do we have them?
Grosz & Sidner ’86
What identifies discourse structure to Hearers?
Textual cues
Spoken cues
How can we produce appropriate discourse structure in TTS systems?
Can we identify discourse structure automatically, from speech?
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3. Is there structure in this discourse?
A beautiful mallard spotted the dove I was feeding.
The duck dove supply is small this year.
That dove was history in a minute.
Well, to recover from this horrible scene, I went to the park snack bar for a cup of cocoa.
To my surprise, I ran into a friend from back home.
When I told her of my recent experience she questioned my sanity.
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4. Is this a reasonable structure?
A beautiful mallard spotted the dove I was feeding.
The duck dove supply is small this year.
That dove was history in a minute.
Well, to recover from this horrible scene, I went to the park snack bar for a cup of cocoa.
To my surprise, I ran into a friend from back home.
When I told her of my recent experience she questioned my sanity.
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5. This? A beautiful mallard spotted the dove I was feeding.
The duck dove supply is small this year.
That dove was history in a minute.
Well, to recover from this horrible scene, I went to the park snack bar for a cup of cocoa.
To my surprise, I ran into a friend from back home.
When I told her of my recent experience she questioned my sanity.
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6. This? A beautiful mallard spotted the dove I was feeding.
The duck dove supply is small this year.
That dove was history in a minute.
Well, to recover from this horrible scene, I went to the park snack bar for a cup of cocoa.
To my surprise, I ran into a friend from back home.
When I told her of my recent experience she questioned my sanity.
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7. What information do we use in segmenting a discourse?
‘Topic’ coherence?
Repeated reference?
‘Cue’ phrases?
????
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8. Structures of Discourse Structure (Grosz & Sidner ‘86)
A leading theory of discourse structure
Based upon Speaker intentions and Speaker and Hearer attentional state
Identifies a few, general relations that hold among Speaker intentions
Identifies a model of attentional state
Three components:
Linguistic structure
Intentional structure
Attentional structure
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9. Linguistic Structure What is actually said or written
How is the linguistic structure represented?
Assume discourse is segmented into Discourse Segments (DS)
What is the basic unit of analysis?
Do we all segment alike?
Do we all use the same cues?
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10. Linguistic Structure of Discourse D
S1: A beautiful mallard spotted the dove I was feeding.
The duck dove supply is small this year.
That dove was history in a minute.
S2: Well, to recover from this horrible scene, I went to the park snack bar for a cup of cocoa.
To my surprise, I ran into a friend from back home.
When I told her of my recent experience she questioned my sanity.
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11. Intentional Structure
Discourse purpose (DP): basic purpose of the Speaker in producing the discourse
Discourse segment purposes (DSPs): the Speaker’s purpose in producing the segment
Segments are related to one another by their purposes:
Satisfaction-precedence: DSP1 must be satisfied before DSP2
Dominance: DSP1 dominates DSP2 if fulfilling DSP2 constitutes part of fulfilling DSP1
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12. Linguistic Structure of Discourse D
DSP1: Describe murder of dove by duck.
S1: A beautiful mallard spotted the dove I was feeding.
The duck dove supply is small this year.
That dove was history in a minute.
DSP2: Describe meeting of old friend.
S2: Well, to recover from this horrible scene, I went to the park snack bar for a cup of cocoa.
To my surprise, I ran into a friend from back home.
When I told her of my recent experience she questioned my sanity.
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13. DSP2: Describe recovery process. S2: DSP3: Describe snack
S3: Well, to recover from this horrible scene, I went to the park snack bar for a cup of cocoa.
DSP3: Describe meeting old friend.
S4: To my surprise, I ran into a friend from back home.
DSP5: Describe friend’s reaction
S5: When I told her of my recent experience she questioned my sanity.
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14. Attentional State: The Focus Stack
Stack of focus spaces, each containing objects, properties and relations salient during each DS, plus the DSP
State changes: transition rules controlling the addition/deletion of focus spaces
Information at lower levels may or may not be available at higher levels
Focus spaces are pushed onto the stack when
A new DS is begun
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15. Focus spaces are popped when they are completed
An embedded DS (e.g. a DS dominated by another DS) is begun
Focus spaces are popped when they are completed
State of focus stack models felicitous reference, coherence in discourse
S2: DSP2, scene, Speaker, snack_bar
Cocoa, friend, home,sanity
S1: DSP1, duck, dove, Speaker,
duck_dove_supply
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16. Limits of the Theory Assumes discourses are task-oriented
Assumes a single, hierarchical structure shared by S and H
Questions:
Do people really build such structures when they converse?
Use them in interpreting what others say?
How could they do it?
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17. How might people recognize discourse structure?
Linguistic markers?
tense and aspect
cue phrases
Inference of Speaker intentions?
Inference from task structure?
Intonational Information?
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18. Acoustic and Prosodic Cues to Discourse Structure
Intuition:
Speakers vary acoustic and prosodic cues to convey variation in discourse structure
Systematic? In read or spontaneous speech?
Evidence:
Observations from recorded corpora
Laboratory experiments
Machine learning of discourse structure from acoustic/prosodic features
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19. Prosodic Correlates of Discourse/Topic Structure
Pitch range
Lehiste ’75, Brown et al ’83, Silverman ’86, Avesani & Vayra ’88, Ayers ’92, Swerts et al ’92, Grosz & Hirschberg’92, Swerts & Ostendorf ’95, Hirschberg & Nakatani ‘96
Preceding pause
Lehiste ’79, Chafe ’80, Brown et al ’83, Silverman ’86, Woodbury ’87, Avesani & Vayra ’88, Grosz & Hirschberg’92, Passoneau & Litman ’93, Hirschberg & Nakatani ‘96
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20. Brown et al ’83, Grosz & Hirschberg’92, Hirschberg & Nakatani ‘96
Rate
Butterworth ’75, Lehiste ’80, Grosz & Hirschberg’92, Hirschberg & Nakatani ‘96
Amplitude
Brown et al ’83, Grosz & Hirschberg’92, Hirschberg & Nakatani ‘96
Contour
Brown et al ’83, Woodbury ’87, Swerts et al ‘92
Add Audix tree??
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21. Issues
Do we find significant and reliable cues to discourse structure in prosodic variation
When tested against an independent theory of discourse structure?
In spontaneous as well as read speech?
Are Hearers interpretations of discourse structure influenced by intonational variation?
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22. Grosz & Hirschberg ‘92 Small corpus of read AP newswire
Read by professional speaker
Labeled for discourse structure from text alone or from text and speech
Pre-ToBI labeled
Acoustic-prosodic features extracted for each intermediate (level 3) phrase
Pitch range and change from prior phrase
Intensity (rms) and change in db from prior phrase
Preceding and subsequent pause
Speaking rate
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23. ANOVA’s and t-tests on means Results:
Analysis of phrases in different segment positions: SBEG, SF, parentheticals, quoted speech
ANOVA’s and t-tests on means
Results:
Direct quotes: larger pitch range
Parentheticals: smaller range, neg change from prior phrase, neg change in db, faster rate
SBEG: larger range, louder, greater preceding pause, less subsequent pause
SF: greater subsequent pause
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24. Machine learning experiments identified:
SBEG with 91.5% est. accuracy (x-validation)
SF, 92.5%
Attributive tags, 96.9%
Direct quotations, 86.4%
Indirect quotations, 88.5%
Parentheticals, 89.2%
Conclusion: Acoustic/prosodic information is available to permit Hearers to identify discourse structure…
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25. Next The midterm Closed book, no notes or electronic devices
Will include material through today
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