Stress
is the property of a language to exhibit prominence or distinction in one or more syllables in a given domain. The existence of word stress has not been suitably explored in previous acoustic studies of the Mizo language, which is a tonal language of the Kuki-Chin sub-category in Tibeto-Burman language families. In this study, we attempt to analyze word stress on disyllabic target words, specifically in three lexical categories—
adjectives, nouns,
and
verbs
. Utterances of the target words are recorded in isolated setting (out of focus) and in sentence frames (in focus). First, averages of features, namely—
duration, intensity, F0, formants
, and
spectral tilt
, are extracted and investigated for identification of
stressed
and
unstressed
syllables on a total of 2,880 samples. Next, the interaction of word stress on the four tones of Mizo is investigated. While it is found that H-tone is generally stressed, inferences are made that stressed syllables are not unique to a specific tone. Third, significance of the selected features are validated using a two-tailed paired sample
t
-test. Our analysis indicates that the mean differences in
duration, intensity,
and
F0
of the
stressed
and
unstressed
syllables are significant across the lexical categories at
p
< 0.05. Next, validations on the significance of the mean differences are carried out using Cohen’s
d
effect size and Pearson’s Correlation Coefficient (
r
). Finally, three machine learning models—Support Vector Machines (SVM), Naive Baye’s, and Ensemble learning methods (AdaBoost and Boosted Aggregation), are used to identify stressed and unstressed syllables associated with tones in Mizo. Discriminating differences, especially in disyllabic
verbs
, are observed between
stressed
vs.
unstressed
syllables. Conclusions are drawn that
duration
is a
strong
and robust cue for acoustic correlates of stress, while
intensity
is a
medium
cue for stress and
F0
a
weak
cue for stress.