Why a Rising Tone is Falling in Mandarin Sentences

Chilin Shih

University of Illinois at Urbana-Champaign

Word Accents and Tones in Sentence Perspective:A symposium in conjunction with the 60th birthday of

Professor Gösta Bruce

January 10, 2007 Lund, Sweden

Generated by WordsEye from text description. Under development at SemanticLight, Inc.

Outline

• What we know– Chinese is a lexical tone language.

• Surprise!– Tones in sentences may deviate considerably

from their lexical specifications.

• Research question– Explain the difference between lexical tones

and the observed sentence production.

• Implication– A simulation model linking phonology to

phonetics.

Chinese Lexical Tones

Tone shapes differentiate lexical meaning.

Ma1: mother

Ma2: hemp

Ma3: horse

Ma4: to scold

Chinese Sentences

Ma1-ma0 ma4 ma3. Mother scolds the horse.

Ma3 ma4 ma1-ma0. The horse scolds mother.

Chinese Intonation Types (Data from JiahongYuan)

Li3bai4wu3 Luo2yan4 yao4 mai3 lu4.

On Friday Luoyan wants to buy a deer.

Statement

Question

Classification of Tone Shapes

Tone 1High level

Tone 2Rising

Tone 3Low falling

Tone 4High falling

Cause of Tonal Distortion

• Ease of articulatory effort

• Balancing articulatory effort and communication need

Physiological constraints:

Communication errors:

• When you say what you think you are saying:

• When you are not saying want you think you are saying:

Ease of Articulatory Effort—I

Ease of Articulatory Effort—II

Ease of Articulatory Effort—III

Production of Rising and Falling Tones

Severe Tonal Distortion—I

People Talk Nearly As Fast As Possible

Severe Tonal Distortion—II

Local distortion is predictable from global optimization

A Racing Game

Adjusting the Best Path

Best Path in Tonal Production

1.0 1.0 1.00.00.5

Stem-ML

The prosodic modeling is based on Stem-ML (Soft Template Mark-up Language).

Stem-ML consists of a set of mathematically defined tags with value attributes.

For example: Tone prosodic strength

Allowing user-defined accent shapes, phrase curves, and other speaker specific parameters.

Kochanski and Shih (2003), Prosody modeling with soft templates, Speech Communication V. 39.Shih (in preparation), Prosody Learning and Generation, Springer.

Basic Assumptions

• Pre-planning.

• Balance articulatory effort and communication needs (Lindblom, Ohala).

• A dynamical model for the muscles that control f0 (Hill).

We further propose:

• Speaker shifts weights dynamically as they speak.

• This is the prosodic strength, which reflects the articulatory effort.

Linking Phonology and Phonetics

• A model is a sequence of templates (i.e. points representing tone/accent shapes). The templates encodes phonological information.

• For tone languages, there is one template per tone. Templates are stretched to fit duration.

• Each template has a strength. The strength value determines phonetic variation.

Representation

Surface F0 contours are coded as a set of Template strength

Generation: Template strength F0

Learning: Template, F0 Template strength

T11.0 T3 0.3 T4 1.2 T5 0.8 T21.0 T1 0.5

Modeling Math (Credit to Greg Kochanski)( )RGtp

tp+=

)(minarg)(

( )∫ ++= 22222 pppdtG ητ &&&

)(tp is the muscle tension (~frequency) at time t.

“Effort”

∑∈

=targets

2

iii rsR Each target encodes some linguistic information, ri

is the error of the ith target, and si is its importance.

( ) ( )( )∫∈ −+−−−=itarget

22)()(ti ypyyppdtr βα

y is the ith pitch target and a bar denotes an average over a target.

“Error”

)(tyy i≡

Representing F0 As Tone Strength

Simulation of Tonal Production—I

Simulation of Tonal Production—II

Model Fits to Mandarin Chinese

0.61 free parameters per syllable, 13 Hz RMS error.

Works for English

*

************************************************************ ********************

************* ************** ***********************

**********************

*********** ****************** *******

****************

F0 (Hz)

1 2 3 4 (s)

200300400

Time

would

Uhm

I

like

A flight to Seattle from Albuquerque

The highest f0 is on a weak, unaccented word.

Interpolation

Muscle Dynamics

Discourse Functions

• Topic initialization

• Discourse structure

• Phrasing

• Emphasis

• New vs. old information

• Other communicative means

How Do They Fit Together?

Conclusion

• Speech is a communication system. Speakers balance articulatory effort and communication needs.

• We need a representation that encodes– Accent template– Articulatory effort– Emotional State

• We present a computational simulation model that generate surface phonetic variations from this representation.