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Emotional Speech. CS 4706 Julia Hirschberg (thanks to Jackson Liscombe and Lauren Wilcox for some slides). Outline. Why study emotional speech? Why is modeling emotional speech so difficult? Production and perception studies Voice Quality features: the holy grail.
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Emotional Speech CS 4706 Julia Hirschberg (thanks to Jackson Liscombe and Lauren Wilcox for some slides)
Outline • Why study emotional speech? • Why is modeling emotional speech so difficult? • Production and perception studies • Voice Quality features: the holy grail CS 4706
Why study emotional speech? • Recognition • Customer-care centers • Tutoring systems • Automated agents (Wildfire) • Generation • Characteristics of ‘emotional speech’ little understood, so hard to produce: …a voice that sounds friendly, sympathetic, authoritative…. • TTS systems • Games CS 4706
Emotion in Spoken Dialogue Systems • Batliner, Huber, Fischer, Spilker, Nöth (2003) • Verbmobil (Wizard of Oz scenarios) • Ang, Dhillon, Krupski, Shriberg, Stolcke (2002) • DARPA Communicator • Liscombe, Guicciardi, Tur, Gokken-Tur (2005) • “How May I Help You?” call center • Lee, Narayanan (2004) • Speechworks call-center • Liscombe, Hirschberg, Venditti (2005) • ITSpoke Tutoring System (physics) CS 4706
Why is emotional speech so hard to model? • Colloquial definitions of speakers and listeners ≠ technical definitions • Utterances may convey multiple emotions simultaneously • Result: • Human consensus low • Hard to get reliable training data CS 4706
Spontaneous Corpora • Unconstrained • [Campbell, 2003] [Roach, 2000] • [Cowie et al., 2001] • Call centers • [Vidrascu & Devillers, 2005] [Ang et al., 2002] • [Litman and Forbes-Riley, 2004] [Batliner et al., 2003] • [Lee & Narayanan, 2005] • Meetings • [Wrede and Shriberg, 2003] CS 4706
Acted Corpora happy sad angry confident frustrated friendly interested anxious bored encouraging CS 4706
LDC Emotional Prosody and Transcripts corpus • Semantically neutral (dates and numbers) • 8 actors • 15 emotions CS 4706
Are Emotions Mutually Exclusive? • User study to classify tokens from LDC Emotional Prosody corpus • 10 emotions only: • Positive: confident, encouraging, friendly, happy, interested • Negative: angry, anxious, bored, frustrated, sad • Example CS 4706
Emotion Intercorrelations (p < 0.001) CS 4706
Results • Emotions are heavily correlated • Positive with positive • Negative with negative • Emotions are non-exclusive • Can they be clustered empirically • Activation • Valency CS 4706
Global Pitch Statistics Different Valence/Activation CS 4706
Identifying Emotions • Automatic Acoustic-prosodic [Davitz, 1964] [Huttar, 1968] • Global characterization • pitch • loudness • speaking rate • Intonational Contours [Mozziconacci & Hermes, 1999] • Spectral Tilt [Banse & Scherer, 1996] [Ang et al., 2002] CS 4706
Machine Learning Experiment • RIPPER 90/10 split • Binary classification for each emotion • Results • 62% average baseline • 75% average accuracy • Acoustic-prosodic features for activation • /H-L%/ for negative; /L-L%/ for positive • Spectral tilt for valence? CS 4706
A Call Center Application • AT&T’s “How May I Help You?” system • Customers often angry and frustrated CS 4706
HMIHY Example VeryFrustrated Somewhat Frustrated CS 4706
Pitch, Energy and Rate CS 4706
Features • Automatic Acoustic-prosodic • Contextual [Cauldwell, 2000] • Lexical [Schröder, 2003] [Brennan, 1995] • Pragmatic [Ang et al., 2002] [Lee & Narayanan, 2005] CS 4706
Results CS 4706
Tutoring Systems Should Respond to Uncertainty • SCoT [Pon-Barry et al. 2006] • Responding to uncertainty • Active listening • Hinting vs. paraphrasing • Features examined • Latency • Filled pauses • Hedges • Performance metric • Learning gain • But no improvement by responding to uncertainty CS 4706
[pr01_sess00_prob58] CS 4706
Uncertainty in ITSpoke um <sigh> I don’t even think I have an idea here ...... now .. mass isn’t weight ...... mass is ................ the .......... space that an object takes up ........ is that mass? [71-67-1:92-113] CS 4706
ITSpoke Experiment • Human-Human Corpus • AdaBoost(C4.5) 90/10 split in WEKA • Classes: Uncertain vs Certain vs Neutral • Results: CS 4706
ITSpoke Results CS 4706
Voice Quality and Emotion • Perceptual coloring • Derived from a variety of laryngeal and supralaryngeal features • modal, creaky, whispered, harsh, breathy, ... • Correlates with emotion • Laver ‘80, Scherer ‘86, Murray& Arnott ’93, Laukkanen ’96, Johnstone & Scherer ’99, Gobl & Chasaide, ‘03, Fernandez ‘00 CS 4706
Phonation Gestures • Adductive tension: interarytenoid muscles adduct the arytenoid muscles • Medial compression: adductive force on vocal processes- adjustment of ligamental glottis • Longitudinal pressure: tension of vocal folds CS 4706
Modal Voice • “Neutral” mode • Muscular adjustments moderate • Vibration of vocal folds periodic, full closing of glottis, no audible friction • Frequency of vibration and loudness in low to mid range for conversational speech CS 4706
Tense Voice • Very strong tension of vocal folds, very high tension in vocal tract CS 4706
Whispery Voice • Very low adductive tension • Medial compression moderately high • Longitudinal tension moderately high • Little or no vocal fold vibration • Turbulence generated by friction of air in and above larynx CS 4706
Creaky Voice • Vocal fold vibration at low frequency, irregular • Low tension (only ligamental part of glottis vibrates) • The vocal folds strongly adducted • Longitudinal tension weak • Moderately high medial compression CS 4706
Breathy Voice • Tension low • Minimal adductive tension • Weak medial compression • Medium longitudinal vocal fold tension • Vocal folds do not come together completely, leading to frication CS 4706
Estimating Voice Quality • Estimate wrt controlled neutral quality • But how do we know the control is truly “neutral”? • Must must match the natural laryngeal behavior to laboratory “neutral” • Our knowledge of models of vocal fold movements may be inadequate for describing real phonation • Known relationships between acoustic signal and voice source are complex • Only can observe behavior of voicing indirectly so prone to error. • Direct source data obtained by invasive techniques which may interfere with signal CS 4706
Next Class • Deceptive Speech CS 4706