Page 207 - Designing Sociable Robots

breazeal-79017 book March 18, 2002 14:16

188 Chapter 11

convey anger, fear, disgust, gladness, sadness, and surprise in synthetic speech. Emotions
have a global impact on speech since they modulate the respiratory system, larynx, vocal
tract, muscular system, heart rate, and blood pressure. The pitch-related parameters affect
the pitch contour of the speech signal, which is the primary contributor for affective infor-
mation. The pitch-related parameters include accent shape, average pitch, pitch contour
slope, final lowering, pitch range, and pitch reference line. The timing-related parameters
modify the prosody of the vocalization, often being reflected in speech rate and stress
placement. The timing-related parameters include speech rate, pauses, exaggeration, and
stress frequency. The voice-quality parameters include loudness, brilliance, breathiness,
laryngealization, pitch discontinuity, and pause discontinuity. The articulation parameter
modifies the precision of what is uttered, either being more enunciated or slurred. I describe
these parameters in detail in the next section.
For Kismet, only some of these parameters are needed since several are inherently tied
to sentence structure—the types and placement of pauses, for instance (see figure 11.1). In
this section, I briefly describe those VAPs that are incorporated into Kismet’s synthesized

Figure 11.1
Kismet’s expressive speech GUI. Listed is a selection of emotive qualities, the vocal affect parameters, and the
synthesizer settings. A user can either manually enter an English phrase to be said, or can request automatically
generated “Kismet-esque” babble. During run-time, Kismet operates in automatic generation mode.