Emotions and Voice Quality: Experiments with Sinusoidal Modeling Authors: Carlo Drioli, Graziano Tisato, Piero Cosi, Fabio Tesser Institute of Cognitive Sciences and Technologies - CNR Department of Phonetics and Dialectology - Padova Voice quality: functions, analysis and synthesis VOQUAL’03 Geneva, August 27-29, 2003

Outline  Objectives and motivations  Voice material  Acoustic indexes and statistical analysis  Neutral to emotive utterance mapping  Experimental results

Objectives and motivations  Long-term goals: - emotive speech analysis/synthesis - improvement of ASR/TTS systems  Short-term goal: - preliminary evaluation of processing tools for the reproduction of different voice qualities  Focus of talk: - analysis/synthesis of different voice qualities corresponding to different emotive intentions  Method: - analysis of voice quality acoustic correlates - definition of a sinusoidal modeling framework to control voice timbre and phonation quality

An emotive voice corpus was recorded with the following characteristics:  two phonological structures ’VCV: /’aba/ and /’ava/.  neutral (N) plus six emotional states:  1 speaker, 7 recordings for each emotive intention, for each word. anger (A), joy (J), fear (F), sadness (SA), disgust (D), surprise (SU). Voice material

Analysis of emotive speech: acoustic correlates Cue extraction and analysis : Intensity, duration, pitch, pitch range, formants. F0 stressed vowel mean and F0 mid values are strongly correlated. F0 mean (global and for stressed vowel), F0 “mid”, and F0 range anger (A) joy (J) fear (F) sadness (SA) disgust (D) surprise (SU) neutral (N)

Analysis of emotive speech: acoustic correlates Cue extraction and analysis (acoustic correlates of voice quality) : Shimmer, Jitter HNR Hammarberg’s index (HammI) difference between energy max in the Hz and Hz frequency bands Spectral flatness (SFM) ratio of the geometric to the arithmetic mean Drop-off of spectral energy above 1000 Hz (Do1000) LS approx. of the spectral tilt above 1000 Hz High- versus low-frequency range relative energy amount (Pe1000)

Analysis of emotive speech: voice quality Voice quality patterns (distance from Neutral): Discriminant analysis: classification scores: 60/70 % for stressed and unstressed vowel Best score: Fear, Anger Voice quality characterization : Anger: harsh voice (/’a/) Disgust: creaky voice (/a/) Joy, Fear, Surprise : breathy voice Classification matrix for stressed vowel:

Processing of emotive speech: method Neutral Emotive transformation based on sinusoidal modeling and spectral processing Neutral sinus. spectral envelope after pitch shift Emotive sinus. spectral envelope after Ts Spectral envelope conversion function ( : mfcc from ) Neutral Spectral conversion model Emotion j Spectral conversion function design: Neutral sinus. spectral envelope Spectral conversion model (Stylianou et Al., 1998) gaussian mixture model conversion parameters

Processing of emotive speech: method Neutral Emotive transformation based on trained model Neutral Target Disgust Target Sadness Disgust Sadness Disgust (Ps+Ts) Sadness (Ps+Ts)

Processing of emotive speech: results Neutral Emotive transformation based on sinusoidal modeling: Neutral Anger Disgust Joy Fear Surprise Sadness Ps+TsPs+Ts+ScTarget

Processing of emotive speech: results Results: Time-stretch and (formant preserving) pitch shift alone can’t account for the principal emotion related cues Spectral conversion can account for some of the emotion cues In general, the method can’t account for cues related to period-to-period variability (i.e., Shimmer, Jitter) The inclusion of a noise model is required to evaluate the effect on HNR Neutral

Conclusions Future work  Refinements of the model (i.e., noise model)  Adaptation to TTS system  Search for the existence of speaker-independent transformation patterns (using multi-speaker corpora).  Sinusoidal framework was found adequate to process emotive information  Need refinements (e.g. noise model, harshness model) to account for all the acoustic correlates of emotions  Results of processing are perceptually good