1. Spoken Dialogue Systems
CS 4705

2. Talking to a Machine….and (often) Getting an Answer
Today’s spoken dialogue systems make it possible to accomplish real tasks without talking to a person
Could Eliza do this?
What do today’s systems do better?
Do they actually embody human intelligence?
Key advances
Stick to goal-directed interactions in a limited domain
Prime users to adopt the vocabulary you can recognize
Partition the interaction into manageable stages
Judicious use of system vs. mixed initiative
10 or 15 years ago we talked about talking to machines, we studied the problems involved, and we even built demo dialogue systems. Today when you talk to a machine, you have a chance of getting a useful answer -- about travel arrangements or your or your finances. What’s made this possible?

3. Dialogue vs. Monologue
Monologue and dialogue both involve interpreting
Information status
Coherence issues
Reference resolution
Speech acts, implicature, intentionality
Dialogue involves managing
Turn-taking
Grounding and repairing misunderstandings
Initiative and confirmation strategies

4. Segmenting Speech into Utterances
What is an `utterance’?
Why is EOU detection harder than EOS?
How does speech differ from text?
Single syntactic sentence may span several turns
A: We've got you on USAir flight 99
B: Yep
A: leaving on December 1.
Multiple syntactic sentences may occur in single turn
A: We've got you on USAir flight 99 leaving on December. Do you need a rental car?
Intonational definitions: intonational phrase, breath group, intonation unit

5. Turns and Utterances
Dialogue is characterized by turn-taking: who should talk next, and when they should talk
How do we identify turns in recorded speech?
Little speaker overlap (around 5% in English --although depends on domain)
But little silence between turns either
How do we know when a speaker is giving up or taking a turn? Holding the floor? How do we know when a speaker is interruptable?

6. Simplified Turn-Taking Rule (Sacks et al)
At each transition-relevance place (TRP) of each turn:
If current speaker has selected A as next speaker, then A must speak next
If current speaker does not select next speaker, any other speaker may take next turn
If no one else takes next turn, the current speaker may take next turn
TRPs are where the structure of the language allows speaker shifts to occur

7. Adjacency pairs set up next speaker expectations
GREETING/GREETING
QUESTION/ANSWER
COMPLIMENT/DOWNPLAYER
REQUEST/GRANT
‘Significant silence’ is dispreferred
A: Is there something bothering you or not? (1.0s)
A: Yes or no? (1.5s)
A: Eh?
B: No.

8. Intonational Cues to Turntaking
Continuation rise (L-H%) holds the floor
H-H% requests a response
L*H-H% (ynq contour)
H* H-H% (highrise question contour)
Intonational contours signal dialogue acts in adjacency pairs

9. Timing and Turntaking How should we time responses in a SDS?
Japanese studies of aizuchi (backchannels) (Koiso et al ‘98, Takeuchi et al ‘02) in natural speech
Lexical information: particles ne and ka ending preceding turn or (in telephone shopping) product names
Length of preceding utterance, f0, loudness, and pause after even more important in predicting turntaking

10. Turntaking and Initiative Strategies
System Initiative
S: Please give me your arrival city name.
U: Baltimore.
S: Please give me your departure city name….
User Initiative
S: How may I help you?
U: I want to go from Boston to Baltimore on November 8.
`Mixed’ initiative
U: I want to go to Boston.
S: What day do you want to go to Boston?

11. Grounding (Clark & Shaefer ‘89)
Conversational participants don’t just take turns speaking….they try to establish common ground (or mutual belief)
Hmust ground a S's utterances by making it clear whether or not understanding has occurred
How do hearers do this?
S: I can upgrade you to an SUV at that rate.
Continued attention
(U gazes appreciatively at S)
Relevant next contribution
U: Do you have a RAV4 available?

12. Acknowledgement/backchannel
U: Ok/Mhmmm/Great!
Demonstration/paraphrase
U: An SUV.
Display/repetition
U: You can upgrade me to an SUV at the same rate?
Request for repair
U: I beg your pardon?

13. Detecting Grounding Behavior
Evidence of system misconceptions reflected in user responses (Krahmer et al ‘99, ‘00)
Responses to incorrect verifications
contain more words (or are empty)
show marked word order (especially after implicit verifications)
contain more disconfirmations, more repeated/corrected info
‘No’ after incorrect verifications vs. other ynq’s
has higher boundary tone
wider pitch range
longer duration
longer pauses before and after
more additional words after it
Signalling whether information is grounded or not (Clark & Wilkes-Gibbs ‘86, Clark & Schaeffer ‘89): presentation/acceptance
120 dialogue for Dutch train info; one version uses explicit verification and oneimplicit; 20 users given 3 tasks; analyzed 443 verification q/a pairs
predicted that responses to correct verifications would be shorter, with unmarked word order, not repeating or correcting information but presenting new information (positive cues) -- principle of least effort
findings: where problems, subjects use more words (or say nothing), use marked word order (especially after implicit verifs), contain more disconfirmations (duh), with more repeated and corrected info
ML experiments (memory based learning) show 97% correct prediction from these features (>8 words or marked word order or corrects info -> 92%)
Krahmer et al ‘99b predicted additional prosodic cues for neg signals: high boundary tone, high pitch range, long duration of ‘nee’ and entire utterance, long pause after ‘nee’, long delay before ‘no’, from 109 negative answers to ynqs of 7 speakers; hyp

14. User information state reflected in response (Shimojima et al ’99, ‘01)
Echoic responses repeat prior information – as acknowledgment or request for confirmation
S1: Then go to Keage station.
S2: Keage.
Experiment:
Identify ‘degree of integration’ and prosodic features (boundary tone, pitch range, tempo, initial pause)
Perception studies to elicit ‘integration’ effect
Results: fast tempo, little pause and low pitch signal high integration
Shimojima et al:
prior observational study produced corpus of task-oriented conversations in japanese: block configuration task, ftf, 2 party
focussed on immediate repeats from responder (not hello/hello, etc)
Consensus labeled ‘degree to which responder seemed to have integrated information’ (1-5)
Chi-sq and t-tests show close corr of ratings and prosodic features
modified tokens’ tempo, ppau and pitch to create prosody favoring very high and very low integration ratings and
presented to subjects to rate, 1-5
Asked what grounding functions were being performed (request-repair or ack)
Over all, fast tempo, little pause and low pitch signal integration

15. Grounding and Confirmation Strategies
U: I want to go to Baltimore.
Explicit
S: Did you say you want to go to Baltimore?
Implicit
S: Baltimore. (H* L- L%)
S: Baltimore? (L* H- H%)
S: What time do you want to leave Baltimore?
No confirmation

16. How do we evaluate Dialogue Systems?
PARADISE framework (Walker et al ’00)
“Performance” of a dialogue system is affected both by what gets accomplished by the user and the dialogue agent and how it gets accomplished
Maximize
Task Success
Minimize
Costs
Efficiency
Measures
Qualitative
Measures

17. What metrics should we use?
Efficiency of the Interaction:User Turns, System Turns, Elapsed Time
Quality of the Interaction: ASR rejections, Time Out Prompts, Help Requests, Barge-Ins, Mean Recognition Score (concept accuracy), Cancellation Requests
User Satisfaction
Task Success: perceived completion, information extracted
2/19/2019

18. User Satisfaction: Sum of Many Measures
Was Annie easy to understand in this conversation? (TTS Performance)
In this conversation, did Annie understand what you said? (ASR Performance)
In this conversation, was it easy to find the message you wanted? (Task Ease)
Was the pace of interaction with Annie appropriate in this conversation? (Interaction Pace)
In this conversation, did you know what you could say at each point of the dialog?
(User Expertise)
How often was Annie sluggish and slow to reply to you in this conversation? (System Response)
Did Annie work the way you expected her to in this conversation? (Expected Behavior)
From your current experience with using Annie to get your , do you think you'd use Annie regularly to access your mail when you are away from your desk? (Future Use)
2/19/2019

19. Performance Model
Weights trained for each independent factor via multiple regression modeling: how much does each contribute to User Satisfaction?
Result useful for system development
Making predictions about system modifications
Distinguishing ‘good’ dialogues from ‘bad’ dialogues
But … can we also tell on-line when a dialogue is ‘going wrong’

20. Identifying Misrecognitions, Awares and User Corrections Automatically (Hirschberg, Litman & Swerts)
Collect corpus from interactive voice response system
Identify speaker ‘turns’
incorrectly recognized
where speakers first aware of error
that correct misrecognitions
Identify prosodic features of turns in each category and compare to other turns
Use Machine Learning techniques to train a classifier to make these distinctions automatically

21. Turn Types
TOOT: Hi. This is AT&T Amtrak Schedule System. This is TOOT. How may I help you?
User: Hello. I would like trains from Philadelphia to New York leaving on Sunday at ten thirty in the evening.
TOOT: Which city do you want to go to?
User: New York.
misrecognition
Here are examples of the 3 turn types we focus on.
correction
aware site

22. Results Reduced error in predicting misrecognized turns to 8.64%
Error in predicting ‘awares’ (12%)
Error in predicting corrections (18-21%)

23. Conclusions
Spoken dialogue systems presents new problems -- but also new possibilities
Recognizing speech introduces a new source of errors
Additional information provided in the speech stream offers new information about users’ intended meanings, emotional state (grounding of information, speech acts, reaction to system errors)
Why spoken dialogue systems rather than web-based interfaces?