Digital Signal Processing Reference
In-Depth Information
(a)
0.75
0
−0.75
(b)
0.75
0
(c)
−0.75
0.75
0
−0.75
0
0.5
1.0
1.5
2.0
2.5
Time (Seconds)
Fig. 5.1
Duration for the utterances of the text
anni dAnamulalo vidyA dAnamu minnA
for three
different emotions
a
disgust,
b
neutral and
c
sarcasm
group. Excitation source features are not used in this work because, from the work
discussed in the previous chapters, it may be observed that there is no appreciable
influence of excitation source features on emotion recognition, during combination.
Speaking rate is a measure of number of syllables or words spoken per unit
time. It is one of the important speaker specific characteristics [
2
]. Speaking rate
variability is clearly observed while expressing different emotions (See Fig.
5.1
).
It is highly influenced by parameters such as duration and frequency of pauses,
vowel durations, gender and age of the speaker [
3
,
4
]. Speaking rate also depends
upon physiological and psychological characteristics of the speaker [
5
]. Generally,
younger people have faster speaking rate and older people speak more slowly for the
above said reasons. Male speakers' speaking rate is slightly faster than that of female
speakers [
5
]. By conscious manipulation of source and system parameters, speaking
rate can be varied by insertion or deletion of pauses of varying lengths at different
levels [
6
,
7
]. This may be achieved due to variations in articulator movements and
change in the excitation source characteristics [
6
]. The effect of changing speaking
rate is clearly observed on prosodic features. Pitch values of spontaneous speech
are highly influenced by the speaking rate variation [
8
]. Fast speech is characterized
by an overall reduction in the pitch range [
7
]. Perceptual observation of fast speech
indicates an increase in the intensity compared to normal speech [
9
]. It is also reported
that dynamic behavior of the feature vectors is greatly disturbed by a change in the
speaking rate [
10
]. Performance of speech systems is also shown to be affected by a
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