VOT in CP.pdf

International Journal of Science and Research (IJSR)
ISSN: 2319-7064
SJIF (2022): 7.942
Volume 12 Issue 7, July 2023
www.ijsr.net
Licensed Under Creative Commons Attribution CC BY
Voice Onset Time of Stop Consonants in Hindi
Speaking Children with Cerebral Palsy
Himani Bansal1
, Satish Kumaraswamy2
Email: himani.bansal12[at]gmail.com
2
Ph. D.
Email: sat8378[at]yahoo.com
Abstract: The current study was conducted for children with CP who are Hindi speakers, to analyze voice onset time (VOT) patterns
associated with stop consonants. The purpose was to gain more detailed insights into how the coordination and timing needed for these
articulations may be affected by the neurodevelopmental disorder ultimately opening up avenues for improved treatment solutions.
Total 20 children in the age group of 6 - 8 years were taken for the study which was divided into two groups: 10 children diagnosed with
spastic CP and 10 typical children speaking Hindi. Measuring VOT through voice analysis helped us gauge the interval lapsing between
releasing a stop closure and voicing onset. The outcomes exhibited considerable variation in VOT values when comparing groups of
children with cerebral palsy (CP) against typical children speaking Hindi. Specifically, CP children showed longer VOT durations
indicating delayed voicing onset compared to controls. These findings point out that children who have cerebral palsy exhibit different
timing and coordination patterns upon pronouncing stop consonants. It is essential to grasp the VOT traits in children with cerebral
palsy. This will aid in creating suitable intervention techniques that enhance their speech comprehensibility and communication skills.
Keywords: Cerebral palsy, Voice onset time, Hindi language, typical children
1. Introduction
Cerebral palsy (CP) is a neurodevelopmental disorder in
which individuals experience conditions such as impaired
muscle tone, mobility challenges and motor skill difficulties
due to developmental brain injuries. Recognizable signs may
appear earlier in life but the manifestation of this condition
can evolve over time - it is usually diagnosed between ages
3 - 5 years old or later. Neurological rehabilitation is
essential when addressing conditions caused by muscle tone
abnormalities while developing physical rehabilitation
therapies along with occupational therapy for individuals
affected by CP are also crucial areas to consider during
treatment. Additionally, people who have been diagnosed
with CP might struggle with other related health co -
morbidities such as epilepsy seizures episodes or cognitive
impairment problems and gastrointestinal function
disturbances. The interdisciplinary nature of the treatment
required means - treating physicians must collaborate
alongside experienced teams composed of neurologists,
orthopedic, psychological, social care specialists and speech
language pathologists in order to manage the condition more
effectively (Gulati & Sondhi 2018).
To improve patient autonomy multidisciplinary teams
should be selected while keeping individual patient needs in
mind. The aim should beto developregularly updated global
treatment care plans. Cerebral palsy impacts several vital
areas such as sensory capabilities, movement abilities and
cognitive function contributing majorly to verbal expression
challenges such as speech, language and communication.
Successful intervention from professional speech - language
therapists can mitigate the impact of these challenges.
Communication difficulties can arise when the
neuromuscular regulation of the speech mechanism is
disrupted. This issue frequently results in poor speech output
among patients with CP. Sadly, a large proportion (about
38%) of children with CP experience impaired speech
functions such as articulation difficulties (Sankar &
Mundkur, 2005). These problems can greatly impact
intelligibility which can limit participation in various
important activities like work or school. Ultimately these
constraints significantly reduce the quality of life
experienced by these individuals. Children diagnosed with
spastic cerebral palsy most commonly experience varying
degrees of dysarthria - one key symptom being the imprecise
manner of articulation. Inaccurate articulatory position and
manner of consonants are two very consistent aspects of CP
dysarthria (Platt, Andrews, Young & Quinn, 1980).
2. Review of Literature
Complete closure within our vocal tracts creates certain
speech sounds called stop consonants. The pressure built up
inside must then be rapidly released - creating a burst - like
effect. Stop consonants make up nearly a third (29%) of all
consonants used in human language and are a valuable
component in communication from any age (Kent & Kim,
2008). In addition to indicating speech intelligibility, stops
also highlight the effective coordination between laryngeal
and supra - laryngeal level mechanisms (Auzou, Ozsancak,
Morris, Jan, Eustache &Hannequin, 2000). To enhance
therapy and differential diagnosis approaches while better
understanding speech intelligibility deficits, it is crucial to
grasp the abnormal pattern of stop consonants. Taking into
account the potential impact of stop consonant production on
speech intelligibility adds weight to this importance (Kay,
2012).
Extensive research has focused on understanding stop
consonants within normal and disordered speech patterns
alike. Various acoustic features associated with these sounds
are under investigation including stop gap, stop burst,
formant transitions and voice onset time (VOT) which has
proven valuable for distinguishing subtypes of dysarthria as
Paper ID: SR23703122244 DOI: 10.21275/SR23703122244 227

ISSN: 2319-7064
SJIF (2022): 7.942
www.ijsr.net
well as exploring connections between VOT values and
overall speech intelligibility. VOT refers to the length of
time that passes between the release of a plosive and the
onset of vibration in the vocal folds; measured in
milliseconds (Rezaei & Salehi, 2006). Researchers note that
individuals with dysarthria exhibit differing characteristics
regarding their VOT depending on factors such as
underlying cause or specific type; however clear
associations between irregularities in VOT levels
specifically and reduced speech intelligibility remain
elusive. Ansel and Kent (1992) analysis did not find any
significant link between VOT and intelligibility scores
amongst individuals with cerebral palsy. In contrast, another
investigation involving Mandarin speakers who also had
cerebral palsy found that VOT variation played a crucial role
in predicting their level of intelligibility (Liu, Tseng & Tsao,
2000).
Singh & Tiwari (2016) said that Hindi language
encompasses a range of non - nasal stops such as velar,
palatal, retroflex, dental and bilabial equivalents pronounced
at varying levels of intensity: voiceless unaspirated or
aspirated; voiced unaspirated or aspirated; as well as nasal
flavours. They also demonstrated that most forms of non -
nasal stops could be generated through the combination of
relatively simple acoustic functions. Pyata&Banik (2016)
studied the phonological development profile in typical
children speaking Hindi and found that all the stop sounds
were achieved in initial, medial & final position in words by
the age of 5 ½ years. Therefore, the age range selected for
the present study was 6 - 8 years.
Despite the use of both acoustic and spectral analysis in
earlier studies on stops and other consonants across several
foreign languages, there is limited published literature
detailing acoustics involved with stop consonants among
normal/disordered populations within Indian Languages
where our research aims to contribute meaningfully.
Samudravijaya (2003) studied durational characteristics of
Hindi stop consonants and found that the post - release
duration of a plosive changes systematically with manner of
articulation. However, due to its large variation in
continuous speech, the post - release duration alone is not
sufficient to identify the manner of articulation of the stop.
A low value of the ratio of the duration of the vowel to the
closure duration of the following plosive is a cue for
gemination in Hindi stop consonants in continuous speech.
Joy & Sreedevi (2019) studied temporal characteristics of
stop consonants in pediatric cochlear implant users. They
used PRAAT software to derive the acoustic measures –
Voice Onset Time (VOT), Burst duration and Closure
duration. The results of the study revealed that children
using CI differed significantly from TDC for a few target
consonants in burst duration and closure duration. However,
VOT did not show any significant difference between
children using CI and TDC.
Jeong, Kim, Sim & Park (2011) studied the maximum
phonation time (MPT) and temporal aspects in Korean stops
in children with spastic cerebral palsy and the results were as
follows: 1) The MPTs of the cerebral palsy (CP) groups,
both Group I and Group II, were significantly shorter than
those of the normal group.2) The closure durations of the
two CP groups were longer than those of the normal group
for all 9 target syllables.3) The aspiration durations of the
two CP groups were longer than those of the normal
group.4) The closure duration of the normal and CP Group I
was significantly different among tense, aspirated and lax.
However, the CP Group II was different from normal.5) The
aspiration duration of the normal and CP Group I was
significantly different among aspirated, tense and lax.
However, the CP Group II was different from normal.6) The
place of articulation influenced less than the manner of
articulation on closure and aspiration duration.
Kim& Kim (2019) did acoustic analysis of Korean stop
sounds in patients with dysarthria and resulted that the
dysarthria group (DG) had longer closure durations,
suggesting slower articulatory movements of the DG than
the normal control group (NC). They further concluded that
the DG has centralized tongue positions, they control the
tenseness and the timing coordination between laryngeal and
supra - laryngeal articulators to distinctively produce
different types of phonation of stops.
3. Methodology
The objective of this study was to analyze the voice onset
time of stop consonants in children with cerebral palsy who
are native Hindi speakers.
Participants:
The present study included total 20 participants, out of
which 10 were diagnosed with spastic cerebral palsy (CP)
and 10 were typical children speaking Hindi (TD). The
participants in both groups were further subdivided into two
groups based on their chronological age i. e., 6.0 - 6.11 years
and 7.0 - 7.11 years. Children with any type of CP other than
spastic and with any associated problems like mental
retardation were excluded from the study.
Procedure:
In order to study the VOT of stop consonants, PRAAT
software was used to record and analyze the voice samples
of each child. Total 5non - nasal voiced unaspiratedstop
consonants of Hindi language were used as stimulus -
bilabial (/b/), dental (/d
̪ /), retroflex (/ɖ/), palatal (/ʤ/) and
velar (/g/). The production of the stops was recorded for all
20 participants in a quiet room with no background noise.
The recorded voice samples were subjected to detailed
analysis to get the VOT for each group of participants.
Data Analysis:
The VOT for each participant was obtained using PRAAT
software. The values were tabulated separately for the CP &
TD group with respect to the two age groups. Descriptive
statistical analysis was thus carried out within the groups
and across the groups to obtain the comparative values of
VOT of stop consonants in CP & TD children.
4. Results
The obtained data was statistically analysed and the results
are discussed below.
Paper ID: SR23703122244 DOI: 10.21275/SR23703122244 228

ISSN: 2319-7064
SJIF (2022): 7.942
www.ijsr.net
Table 1: Showing comparison of mean voice onset time of typical children within the group
VOT of TD within group (in seconds)
S. NO. Consonant 6.0 - 6.11 yrs 7.0 - 7.11 yrs p value
Mean SD Mean SD
1 Bilabial /b/ 0.260 0.054 0.255 0.018 0.850
2 Dental /d
̪ / 0.361 0.121 0.229 0.033 0.048
3 Retroflex /ɖ/ 0.261 0.063 0.259 0.020 0.963
4 Palatal /ʤ/ 0.316 0.103 0.284 0.023 0.512
5 Velar /g/ 0.291 0.080 0.243 0.027 0.242
Figure 1: Showing comparison of mean voice onset time of typical children within the group
The comparative values of mean voice onset time of typical children within the group showed significant difference for
dental stop consonant /d
̪ /.
Table 2: Showing comparison of mean voice onset time of CP children within the group
VOT of CP within group (in seconds)
Mean SD Mean SD
1 Bilabial /b/ 0.348 0.083 0.382 0.086 0.551
2 Dental /d
̪ / 0.407 0.110 0.438 0.051 0.582
3 Retroflex /ɖ/ 0.428 0.092 0.441 0.051 0.799
4 Palatal /ʤ/ 0.434 0.050 0.466 0.035 0.276
5 Velar /g/ 0.332 0.068 0.363 0.062 0.471
Figure 2: Showing comparison of mean voice onset time of CP children within the group
Paper ID: SR23703122244 DOI: 10.21275/SR23703122244 229

ISSN: 2319-7064
SJIF (2022): 7.942
www.ijsr.net
The comparative values of mean voice onset time of CP children within the group showed no significant difference for any of
the stop consonants.
Table 3: Showing comparison of mean voice onset time across the groups for the age range of 6.0 - 6.11 years
VOT across the groups (in seconds) - TD CP
Mean SD Mean SD
1 Bilabial /b/ 0.260 0.054 0.348 0.497 0.08
2 Dental /d
̪ / 0.361 0.121 0.407 1.022 0.55
3 Retroflex /ɖ/ 0.261 0.063 0.428 1.642 0.01
4 Palatal /ʤ/ 0.316 0.103 0.434 2.191 0.05
5 Velar /g/ 0.291 0.080 0.332 2.782 0.41
Figure 3: Showing comparison of mean voice onset time across the groups for the age range of 6.0 - 6.11 years
The comparative values of mean voice onset time across the groups for the age range of 6.0 - 6.11 years showed highly
significant difference for bilabial /b/, retroflex /ɖ/ and palatal /ʤ/ stop consonants in Hindi.
Table 4: Showing comparison of mean voice onset time across the groups for the age range of 7.0 - 7.11 years
VOT across the groups (in seconds) - TD CP
Mean SD Mean SD
1 Bilabial /b/ 0.255 0.018 0.382 0.086 0.01
2 Dental /d
̪ / 0.229 0.033 0.438 0.051 0.00
3 Retroflex /ɖ/ 0.259 0.020 0.441 0.051 0.00
4 Palatal /ʤ/ 0.284 0.023 0.466 0.035 0.00
5 Velar /g/ 0.243 0.027 0.363 0.062 0.00
Figure 4: Showing comparison of mean voice onset time across the groups for the age range of 7.0 - 7.11 years
Paper ID: SR23703122244 DOI: 10.21275/SR23703122244 230

ISSN: 2319-7064
SJIF (2022): 7.942
www.ijsr.net
The comparative values of mean voice onset time across the
groups for the age range of 7.0 - 7.11 years showed highly
significant difference for bilabial /b/, dental /d
̪ /, retroflex /ɖ/,
palatal /ʤ/ and velar /g/ stop consonants in Hindi.
5. Discussion
The present study is a useful reference for comprehending
an important temporal aspect of stop consonants, voice onset
time, in typical children and children with cerebral palsy
speaking Hindi in the age range of 6 to 8 years. The
comparative values of mean VOT across the groups for the
age range of 6.0 - 6.11 years showed highly significant
difference for bilabial /b/, retroflex /ɖ/ and palatal /ʤ/ stop
consonants. Whereas, the comparative values of mean voice
onset time across the groups for the age range of 7.0 - 7.11
years showed highly significant difference for bilabial /b/,
dental /d
̪ /, retroflex /ɖ/, palatal /ʤ/ and velar /g/ stop
consonants in Hindi. It can be clearly concluded from the
results that children with spastic CP have significantly
longer VOT as compared to typical children speaking Hindi.
Considering the results of study undertaken by Liu, Tseng &
Tsao (2000), the findings of the present study can be helpful
in predicting speech intelligibility in children with cerebral
palsy speaking Hindi. This research work also aligns with
the results of Kim & Kim (2019) who compared the acoustic
features of Korean stop sounds between adults in dysarthric
and typical developing group.
6. Summary & Conclusion
The study at hand offers valuable information on the
temporal characteristic, i. e., voice onset time in stop
consonants for children between the ages of 6 and 8 years
old who speak Hindi, both those developing typically and
those with spastic cerebral palsy. Furthermore, this study
seeks to contrast the mean VOTs within the groups and
across the groups for typical children and children with
spastic CP speaking Hindi in the age range of 6 - 8 years.
For this purpose, total five non - nasal, voiced and
unaspirated stop consonants of Hindi language were used a
stimulus - bilabial (/b/), dental (/d
̪ /), retroflex (/ɖ/), palatal
(/ʤ/) and velar (/g/). The voice recordings for all the
participants were done and VOTs were tabulated using
PRAAT software followed by descriptive statistical analysis
to get the comparative values of mean VOT within and
across the target groups. The across groups comparative
values for the age range of 6.0 - 6.11 years showed highly
significant difference for bilabial /b/, retroflex /ɖ/ and palatal
/ʤ/ stop consonants. Whereas, the comparative values of
mean voice onset time across the groups for the age range of
7.0 - 7.11 years showed highly significant difference for
bilabial /b/, dental /d
̪ /, retroflex /ɖ/, palatal /ʤ/ and velar /g/
stop consonants in Hindi. The results indicated statistically
significant prolonged VOT in children with spastic CP as
compared to that of typical children speaking Hindi.
7. Clinical Implications
The results of the present study can be effectively applied in
clinical settings by the SLPs to understand the temporal
characteristics of stop consonants in children with spastic
cerebral palsy and their correlation with speech
intelligibility. This understanding and correlation is
important for the implementation of an effective intervention
program.
8. Limitations
This research work has a few limitations like limited sample
size and age groups.
9. Future Recommendations
Expanding participant population sizes and age groups -
alongside investigating alternative Indian languages - will
further enhance the scope and depth of the current research.
References
[1] Ansel, B. M., & Kent, R. D. (1992). Acoustic -
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[2] Auzou, P., Ozsancak, C., Morris, R. J., Jan, M.,
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[3] Gulati, S., & Sondhi, V. (2018). Cerebral palsy: an
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Paper ID: SR23703122244 DOI: 10.21275/SR23703122244 231

ISSN: 2319-7064
SJIF (2022): 7.942
www.ijsr.net
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Author Profile
Himani Bansal, Postgraduate Student, Dr. M. V.
Shetty College of Speech and Hearing, Mangalore
575015, Karnataka, India
+918604987167
himani. bansal12[at]gmail.com
Dr. Satish Kumaraswamy, Ph. D., Professor &
Principal, Dr. M. V. Shetty College of Speech and
Hearing, Mangalore 575015, Karnataka, 2India.
+9199741627640
sat8378[at]yahoo.com
Paper ID: SR23703122244 DOI: 10.21275/SR23703122244 232

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